Methods and compositions using fgf23 fusion ppolypeptides

ABSTRACT

The present disclosure is directed to methods, kits and compositions for preventing or treating age-related conditions or metabolic disorders. The fusion polypeptides of the disclosure include FGF23 or an active fragment thereof. In one embodiment, the fusion polypeptide comprises (a) a polypeptide comprising fibroblast growth factor 23 (FGF23), or a functionally active variant or derivative thereof, wherein FGF23 has a mutation at one or more of the positions Q156, C206 and C244; and (b) either a modified Fc fragment having decreased affinity for Fc-gamma-receptor and/or increased serum half-life, or a polypeptide comprising at least one extracellular subdomain of a Klotho protein, or a functionally active variant or derivative thereof; and, optionally (c) a linker. The Klotho fusion proteins are useful in the treatment and prevention of a variety of age-related conditions and metabolic disorders. In another embodiment, the fusion polypeptide comprises a FGF (such as FGF23), or a functionally active variant or derivative thereof; and a modified Fc fragment, or a functionally active variant or derivative thereof. In various embodiments of the fusion polypeptides, FGF23 has mutations which decrease aggregation and protease-mediated cleavage.

This application claims priority to U.S. application Ser. No. 12/696693,filed Jan. 29, 2010, the contents of which are incorporated herein byreference in their entirety.

1. BACKGROUND

Fibroblast growth factors (FGFs) constitute a family of homologouspolypeptide growth factors expressed in many organisms (Ornitz and Itoh,Genome Biol. 2: reviews, 3005.1-3005.12 (2001)). Among vertebratespecies, FGFs are highly conserved in both gene structure and amino-acidsequence, having between 13-71% amino acid identity with one another. Inhumans, there are 22 known members of the FGF family (FGF15 is the mouseortholog of human FGF19, hence there is no human FGF15). During earlydevelopment, FGFs regulate cell proliferation, migration, anddifferentiation, but in the adult organism, FGFs maintain homeostasis,function in tissue repair, and respond to injury.

FGFs function as growth factors by binding and thereby activatingcell-surface FGF receptors. FGF receptors (FGFRs) are tyrosine kinasereceptors that activate signal transduction through autophosphorylationof FGFR, phosphorylation of FRS2 (FGF receptor substrate 2) and ERK1/2(extracellular signal-regulated protein kinase 1/2), and activatingEgr-1 (early growth response-1). FGFs also have a high affinity forheparin sulfate proteoglycans. When bound to FGFs, heparin sulfateenhances the activation of FGFRs.

The alpha-Klotho gene encodes a 130 kDa single pass type I transmembraneprotein with an extracellular domain and a short cytoplasmic domain. Theextracellular domain of alpha-Klotho protein comprises two subdomainstermed, KL-D1 and KL-D2. These two subdomains share sequence homology toβ-glucosidase of bacteria and plants. The extracellular domain of thealpha-Klotho protein may be bound to the cell surface by thetransmembrane domain or may be cleaved and released into theextracellular milieu. Cleavage of the extracellular domain appears to befacilitated by local low extracellular Ca²⁺ concentrations.

In addition to alpha-Klotho, a homolog of alpha-Klotho, beta-Klotho, hasbeen identified (Ito et al., Mech. Dev. 98:115-9 (2000)). Beta-Klotho isalso a single pass type I transmembrane protein with extracellular KL-D1and KL-D2 subdomains.

Modulation of alpha-Klotho expression has been demonstrated to produceaging related characteristics in mammals. Mice homozygous for a loss offunction mutation in the alpha-Klotho gene develop characteristicsresembling human aging, including shortened lifespan, skin atrophy,muscle wasting, arteriosclerosis, pulmonary emphysema and osteoporosis(Kuro-o et al., Nature, 390:45-51 (1997)). In contrast, overexpressionof the alpha-Klotho gene in mice extends lifespan and increasesresistance to oxidative stress relative to wild-type mice (Kurosu etal., Science 309:1829-1833 (2005); Yamamoto et al., J. Biol. Chem.280:38029-38034 (2005)).

Recent studies have demonstrated strikingly similar biologicalcharacteristics between FGF23-deficient mice and alpha-Klotho-deficientmice (Shimada et al., J. Clin. Invest. 113:561-568 (2004); Yoshida etal. Endocrinology 143:683-689 (2002)), indicating functional crosstalkbetween FGF23 and alpha-Klotho. These studies led to the identificationof alpha-Klotho as an obligatory partner of FGF23, in terms of bothbinding and signaling through its cognate FGF receptors (Urakawa et al.,Nature 22:1524-6 (2007)). The alpha-Klotho gene is mainly expressed inkidney, parathyroid gland and choroid plexus. It is hypothesized thatthe tissue-specific expression of alpha-Klotho restricts activation ofFGF23 signaling to those tissues.

Similar to FGF23/alpha-Klotho, beta-Klotho is an obligatory partner ofFGF19 and FGF21, both in binding and in signaling through theirrespective cognate FGF receptors (Ogawa et al., Proc. Natl. Acad. Sci.USA 104:7432-7 (2007); Lin et al., J. Biol Chem. 282:27227-84 (2007);and Wu et al., J. Biol. Chem. 282:29069-72 (2007)). Such studies havealso demonstrated the involvement of beta-Klotho in regulatingtissue-specific metabolic activity. Beta-Klotho was initially shown toact with FGF21 as a cofactor for regulating carbohydrate and lipidmetabolism in adipose tissue. Beta-Klotho in conjunction with FGF19regulates bile acid metabolism in liver, thus explaining elevated bilesynthesis in beta-Klotho deficient mice (Ito et al., J Clin Invest. 2005August; 115(8):2202-8).

U.S. Pat. No. 6,579,850 describes polypeptides and compositionscomprising an alpha-Klotho polypeptide. Human and mouse alpha-Klothopolypeptides are disclosed. The patent also disclosed that compositionscomprising the polypeptides are useful in treating a syndrome resemblingpremature aging, treating adult diseases, and suppressing aging.

U.S. Pat. No. 7,223,563 describes isolated nucleic acids encoding theFGF23 polypeptide sequence or recombinant cells comprising such anisolated nucleic acid. The patent further relates to methods ofdiagnosing and treating hypophosphatemic and hyperphosphatemicdisorders, osteoporosis, dermatomyositis, and coronary artery disease.

U.S. Pat. No. 7,259,248 describes isolated nucleic acids encoding theFGF21 polypeptide sequence. The patent further relates to methods ofdiagnosing and treating liver disease, conditions related to thymicfunction, and methods of treating conditions of the testis.

2. SUMMARY OF THE INVENTION

The present disclosure is directed to methods, uses, kits andcompositions for preventing or treating age-related conditions ormetabolic disorders with fusion polypeptides or soluble polypeptides.The fusion polypeptides of the present disclosure are formed of a FGF(e.g., FGF23); and either a Klotho protein or an active fragment thereof(e.g., sKlotho) and/or a Fc fragment (e.g., FcLALA); and, optionally, alinker. In some embodiments, the FGF23 is mutated. In some embodiments,the present disclosure provides a Klotho fusion polypeptide comprising aKlotho protein or an active fragment thereof and a fibroblast growthfactor or an active fragment thereof. In some embodiments, the fusionpolypeptide comprises a Klotho polypeptide, a FGF (such as FGF23) and amodified Fc fragment. The Fc fragment can, for example, have decreasedbinding to Fc-gamma-receptor and increased serum half-life. Fusionproteins comprising sKlotho, FGF23 and FcLALA (a modified Fc fragmenthaving decreased affinity for Fc-gamma-receptorand/or increased serumhalf-life) are described in SEQ ID NOs. 46, 47, 48, and 49. In someembodiments, the fusion polypeptide or protein comprises a FGF (e.g.,FGF23), or a functionally active variant or derivative (e.g., a variantcomprising at least one conservative amino acid substitution and/or oneamino acid deletion) thereof; and a modified Fc fragment, or afunctionally active variant or derivative (e.g., a variant comprising atleast one conservative amino acid substitution and/or one amino aciddeletion) thereof. Fusion proteins comprising FGF23 and FcLALA aredescribed in SEQ ID NOs. 50, 51, 52 and 53. In some embodiments, thefusion polypeptide has one or more mutations in FGF23 which decreaseaggregation and/or protease-mediated cleavage.

In a first aspect, the disclosure provides a fusion polypeptide havingat least one extracellular subdomain of a Klotho protein and afibroblast growth factor or an active fragment thereof. In someembodiments, the fusion further comprises a modified Fc fragment havingdecreased affinity (e.g., decreased Ka or increased Kd) forFc-gamma-receptorand/or increased serum half-life. The Klothoextracellular domain may be derived from either the alpha or beta Klothoisoforms. Further, although the FGF component of the Klotho fusionpolypeptide is described primarily with reference to fibroblast growthfactor-19, fibroblast growth factor-21 and fibroblast growth factor-23,it is contemplated that any of the twenty-three known FGFs can be usedin practicing the disclosure. The reader of the instant application mayassume that each of every combination of alpha or beta extracellulardomain with each human FGF protein or an active fragment thereof areindividually and specifically contemplated.

According to the present disclosure, the extracellular domain of theKlotho protein can include one or both of the KL-D1 and KL-D2 domains ofa Klotho protein, or a functionally active variant or derivative (e.g.,a variant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof. In some embodiments, the Klothofusion polypeptide of the disclosure has at least two extracellularsubdomains of a Klotho protein, or a functionally active variant orderivative (e.g., a variant comprising at least one conservative aminoacid substitution and/or one amino acid deletion) thereof. For example,the at least two extracellular subdomains can be at least two KL-D1domains in tandem repeats, at least two KL-D2 domains in tandem repeats,or at least one KL-D1 domain and at least one KL-D2 domain. In variousembodiments, the fusion polypeptide of the disclosure comprises aminoacids 28-292 of the full length alpha Klotho protein, or amino acids28-982 (SEQ ID NO: 7). In another embodiment, the fusion polypeptide ofthe disclosure comprises amino acids 52-997 of the full length betaKlotho protein.

In one embodiment of the present disclosure, the components of a fusionpolypeptide comprise: (a) a polypeptide comprising fibroblast growthfactor 23 (FGF23), or a functionally active variant or derivative (e.g.,a variant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof, wherein FGF23 has a mutation atone or more of the positions Q156, C206 and C244; and (b) either amodified Fc fragment having decreased affinity for Fc-gamma-receptorand/or increased serum half-life, or a polypeptide comprising at leastone extracellular subdomain of a Klotho protein, or a functionallyactive variant or derivative (e.g., a variant comprising at least oneconservative amino acid substitution and/or one amino acid deletion)thereof; and, optionally (c) a linker. The components can be, forexample, chemically linked or fused in frame by a peptide bond. They mayalso linked via a linker. Non-limiting examples of polypeptide linkerare SEQ ID NOs: 11, 12, 13, 14, 15, 16, 17, and 18. Such linkers maycomprise at least one and up to about 30 repeats of SEQ ID NOs:11, 12,13, 14, 15, 16, 17 and 18. In another non-limiting embodiment, thefusion comprises (2) a FGF or an active fragment thereof and (3) amodified Fc fragment. The various components of the fuion can beoperatively linked in any order; the polypeptide (1) can be operativelylinked to the N-terminus of the polypeptide for (2) or (3); thepolypeptide for (2) can be operatively linked to the N-terminus of thepolypeptide for (1) or (3); the polypeptide for (3) can be operativelylinked to the N-terminus of the polypeptide for (1) or (2).

According to the present disclosure, the extracellular subdomain of aKlotho protein, the fibroblast growth factor and the (optional) modifiedFc fragment having decreased affinity for Fc-gamma-receptorand/orincreased serum half-life can be operatively linked to one another in avariety of orientations and manners. For example, the extracellularsubdomain of the Klotho protein can be operatively linked to theN-terminus of the fibroblast growth factor or alternatively thefibroblast growth factor can be operatively linked to the N-terminus ofan extracellular subdomain of the Klotho protein.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of a Klotho protein and a linker. In anotherembodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of the alpha Klotho protein and a linker. Inanother embodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of the beta Klotho protein and a linker In yetanother embodiment, the present disclosure provides a human FGF proteinor an active fragment thereof (e.g., without signal peptide) and alinker. In one embodiment the disclosure provides fusion proteins,nucleic acid molecules or pharmaceutical composition for use in therapyor as medicament for use in the treatment of a pathological disorder.Pharmaceutical compositions comprising the fusion proteins of thedisclosure and their uses for treating or preventing age-relatedconditions or metabolic disorders are also encompassed by the presentdisclosure. In some embodiments, the fusion protein further comprises amodified Fc fragment having decreased affinity forFc-gamma-receptorand/or increased serum half-life.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of alpha Klotho protein with signal peptide fused(directly or indirectly via a linker) to FGF-23. In another embodiment,the present disclosure provides a fusion polypeptide comprising asKlotho of alpha Klotho protein without signal peptide fused (directlyor indirectly via a linker) to FGF-23. In another embodiment, thepresent disclosure provides sKlotho of alpha Klotho protein with signalpeptide fused (directly or indirectly via a linker) to FGF-23 withoutsignal peptide. In another embodiment, the present disclosure provides afusion polypeptide comprising sKlotho of alpha Klotho protein withoutsignal peptide fused (directly or indirectly via a linker) to FGF-23without signal peptide. In some embodiments, the fusion protein furthercomprises a modified Fc fragment having decreased affinity forFc-gamma-receptorand/or increased serum half-life.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of alpha Klotho protein with signal peptide fused(directly or indirectly via a linker) to FGF-23 (R179Q) variant. Inanother embodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of alpha Klotho protein without signal peptidefused (directly or indirectly via a linker) to FGF-23 (R179Q) variant.In another embodiment, the present disclosure provides sKlotho of alphaKlotho protein with signal peptide fused (directly or indirectly via alinker) to FGF-23 (R179Q) variant without signal peptide. In anotherembodiment, the present disclosure provides a fusion polypeptidecomprising sKlotho of alpha Klotho protein without signal peptide fused(directly or indirectly via a linker) to FGF-23 (R179Q) variant withoutsignal peptide. In some embodiments, the fusion protein furthercomprises a modified Fc fragment having decreased affinity forFc-gamma-receptorand/or increased serum half-life.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising: (a) a polypeptide comprising fibroblast growth factor 23(FGF23), or a functionally active variant or derivative (e.g., a variantcomprising at least one conservative amino acid substitution and/or oneamino acid deletion) thereof, wherein FGF23 has a mutation at one ormore of the positions Q156, C206 and C244; and (b) either a modified Fcfragment having decreased affinity for Fc-gamma-receptor and/orincreased serum half-life, or a polypeptide comprising at least oneextracellular subdomain of a Klotho protein, or a functionally activevariant or derivative (e.g., a variant comprising at least oneconservative amino acid substitution and/or one amino acid deletion)thereof; and, optionally (c) a linker. Such fusion polypeptides aredisclosed in SEQ ID NOs: 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,66, 67, and 68.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising (1) sKlotho of alpha Klotho protein with signal peptide, or afunctionally active variant or derivative (e.g., a variant comprising atleast one conservative amino acid substitution and/or one amino aciddeletion) thereof; (2) a linker; and (3) FGF-23 (R179Q) variant withoutsignal peptide, or a functionally active variant or derivative (e.g., avariant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof. In another embodiment, thepresent disclosure provides a fusion polypeptide comprising (1) sKlothoof alpha Klotho protein without signal peptide, or a functionally activevariant or derivative (e.g., a variant comprising at least oneconservative amino acid substitution and/or one amino acid deletion)thereof; (2) a linker; and (3) FGF-23 (R179Q) variant without signalpeptide, or a functionally active variant or derivative (e.g., a variantcomprising at least one conservative amino acid substitution and/or oneamino acid deletion) thereof. In some embodiments, the fusionpolypeptides of the disclosure are glycosylated. In some embodiments,the fusion protein further comprises a modified Fc fragment havingdecreased affinity for Fc-gamma-receptorand/or increased serumhalf-life.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising (1) sKlotho of alpha Klotho protein with signal peptide (SEQID NO: 44 or SEQ ID NO: 45), or a functionally active variant orderivative (e.g., a variant comprising at least one conservative aminoacid substitution and/or one amino acid deletion) thereof (2) a linkercomprising SEQ ID NO: 11; and (3) FGF-23 (R179Q) variant without signalpeptide (SEQ ID NO: 43), or a functionally active variant or derivative(e.g., a variant comprising at least one conservative amino acidsubstitution and/or one amino acid deletion) thereof. In anotherembodiment, the present disclosure provides a fusion polypeptidecomprising (1) sKlotho of alpha Klotho protein without signal peptide(SEQ ID NO: 7), or a functionally active variant or derivative (e.g., avariant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof (2) a linker comprising SEQ IDNO: 11; and (3) FGF-23 (R179Q) variant without signal peptide (SEQ IDNO: 43), or a functionally active variant or derivative (e.g., a variantcomprising at least one conservative amino acid substitution and/or oneamino acid deletion) thereof In one embodiment, the present disclosureprovides a fusion polypeptide comprising the amino acid sequence of SEQID NO: 19, 20, 40, or 41. In some embodiments, the fusion polypeptidesof the disclosure are glycosylated.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising sKlotho of alpha Klotho protein with signal peptide (SEQ IDNO: 44 or SEQ ID NO: 45), or a functionally active variant or derivative(e.g., a variant comprising at least one conservative amino acidsubstitution and/or one amino acid deletion) thereof; and a linkercomprising SEQ ID NO: 11. In another embodiment, the present disclosureprovides a fusion polypeptide comprising sKlotho of alpha Klotho proteinwithout signal peptide (SEQ ID NO: 7); and a linker comprising SEQ IDNO: 11. In some embodiments, the fusion polypeptides of the disclosureare glycosylated. In some embodiments, the fusion protein furthercomprises a modified Fc fragment having decreased affinity forFc-gamma-receptorand/or increased serum half-life.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising a human FGF protein or an active fragment thereof (e.g.,without the signal peptide); and a linker comprising SEQ ID NO: 11. Insome embodiments, the fusion polypeptides of the disclosure areglycosylated. In some embodiments, the fusion protein further comprisesa modified Fc fragment having decreased affinity forFc-gamma-receptorand/or increased serum half-life.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising a human FGF protein (e.g., FGF23) or an active fragmentthereof (e.g., without the signal peptide); a linker (e.g., a linkercomprising SEQ ID NO: 11); and sKlotho (with or without a signalpeptide), or a functionally active variant or derivative (e.g., avariant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof) or a Fc-gramma-receptor (e.g.,FcLALA); wherein the FGF (e.g., FGF23) has one or more mutations atthese residues: R179, Q156, C206, and/or C244. In various embodiments,the mutations are R179Q, Q156A, C2065, and/or C244S. Even though thesemutations are conserved in the human, rhesus, bovine, mouse and ratFGF23, mutating them does not prevent FGF23 activity. Rather, mutatingthese amino acids unexpectedly enhances the qualities of the proteins,by reducing aggregation, reducing undesired protease-induced cleavage,and increasing protein production from cells. In various embodiments,the fusion protein comprising one or more FGF23 mutation isglycosylated.

In one embodiment, the present disclosure provides a pharmaceuticalcomposition (e.g., in an intra-muscular administering form) comprising(e.g., as a sole pharmaceutically active ingredient) a fusionpolypeptide (e.g., glycosylated or non-glycosylated) that comprises (1)FGF-23 (R179Q) variant without signal peptide (SEQ ID NO: 43), or avariant comprising additional mutations which reduce aggregation and/orprotease-mediated cleavage, or a functionally active variant orderivative (e.g., a variant comprising at least one conservative aminoacid substitution and/or one amino acid deletion) thereof (2)optionally, a linker comprising SEQ ID NO: 11; and (3) sKlotho of alphaKlotho protein with signal peptide (SEQ ID NO: 44 or SEQ ID NO: 45), ora functionally active variant or derivative (e.g., a variant comprisingat least one conservative amino acid substitution and/or one amino aciddeletion) thereof or a modified Fc fragment having decreased affinityfor Fc-gamma-receptorand/or increased serum half-life; and uses of thepharmaceutical composition in therapy or as medicament for the treatmentof a pathological disorder, for example treating and/or preventingage-related conditions, such as muscular atrophy. In another embodiment,the present disclosure provides a pharmaceutical composition (e.g., inan intra-muscular administering form) comprising (e.g., as a solepharmaceutically active ingredient) a fusion polypeptide (e.g.,glycosylated or non-glycosylated) that comprises (1) FGF-23 (R179Q)variant without signal peptide (SEQ ID NO: 43), or a variant comprisingadditional mutations which reduce aggregation and/or protease-mediatedcleavage, or a functionally active variant or derivative (e.g., avariant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof (2) a linker comprising SEQ IDNO: 11; and (3) sKlotho of alpha Klotho protein without signal peptide(SEQ ID NO: 7), or a functionally active variant or derivative (e.g., avariant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof, or a modified Fc fragmenthaving decreased affinity for Fc-gamma-receptorand/or increased serumhalf-life, or a functionally active variant or derivative (e.g., avariant comprising at least one conservative amino acid substitutionand/or one amino acid deletion) thereof; and uses of the pharmaceuticalcomposition in therapy or as medicament for the treatment of apathological disorder, for example treating and/or preventingage-related conditions, such as muscular atrophy. In one embodiment, thepresent disclosure provides a pharmaceutical composition (e.g., in anintra-muscular administering form) comprising (e.g., as a solepharmaceutically active ingredient) a fusion polypeptide (e.g.,glycosylated or non-glycosylated) comprising the amino acid sequence ofSEQ ID NO: 19, 20, 40, or 41; and uses of the pharmaceutical compositionin therapy or as medicament for the treatment of a pathologicaldisorder, for example treating and/or preventing age-related conditions,such as muscular atrophy.

In one embodiment, the present disclosure provides a pharmaceuticalcomposition (e.g., in an intra-muscular administering form) comprising(e.g., as a sole pharmaceutically active ingredient) a fusionpolypeptide (e.g., glycosylated or non-glycosylated) that comprisessKlotho of alpha Klotho protein with signal peptide (SEQ ID NO: 44 orSEQ ID NO: 45); and a linker comprising SEQ ID NO: 11; and uses of thepharmaceutical composition for treating and/or preventing age-relatedconditions, such as muscular atrophy. In another embodiment, the presentdisclosure provides a pharmaceutical composition (e.g., in anintra-muscular administering form) comprising (e.g., as a solepharmaceutically active ingredient) a fusion polypeptide (e.g.,glycosylated or non-glycosylated) comprising sKlotho of alpha Klothoprotein without signal peptide (SEQ ID NO: 7); and a linker comprisingSEQ ID NO: 11; and uses of the pharmaceutical composition in therapy oras medicament for the treatment of a pathological disorder,for exampletreating and/or preventing age-related conditions, such as muscularatrophy. In some embodiments, the fusion protein further comprises amodified Fc fragment.

In one embodiment, the present disclosure provides a pharmaceuticalcomposition comprising (e.g., as a sole pharmaceutically activeingredient) a fusion polypeptide (e.g., glycosylated ornon-glycosylated) that comprises a human FGF protein or an activefragment thereof (e.g., without the signal peptide); and a linkercomprising SEQ ID NO: 11.

Pharmaceutical compositions comprising the fusion proteins of thedisclosure and their uses in therapy or as medicament for the treatmentof a pathological disorder therapy, for example treating or preventingage-related conditions (e.g., muscle atrophy) or metabolic disorders(e.g., diabete) are also encompassed by the present disclosure.

In one embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% identical to SEQ ID NO: 19. In anotherembodiment, the present disclosure provides a fusion polypeptide that isat least 85%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 96%, at least 97%, atleast 98%, at least 99% identical to SEQ ID NO: 20.

In one embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% identical to SEQ ID NO: 40. In anotherembodiment, the present disclosure provides a fusion polypeptide that isat least 85%, at least 90%, at least 91%, at least 92%, at least 93%, atleast 94%, at least 95%, at least 96%, at least 96%, at least 97%, atleast 98%, at least 99% identical to SEQ ID NO: 41.

In one embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% or 100% identical to SEQ ID NO: 46. Inanother embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% or 100% identical to SEQ ID NO: 47.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 48. In another embodiment, the present disclosure provides afusion polypeptide that is at least 85%, at least 90%, at least 91%, atleast 92%, at least 93%, at least 94%, at least 95%, at least 96%, atleast 96%, at least 97%, at least 98%, at least 99% or 100% identical toSEQ ID NO: 49.

In one embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% or 100% identical to SEQ ID NO: 50. Inanother embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% or 100% identical to SEQ ID NO: 51.

In one embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% or 100% identical to SEQ ID NO: 52. Inanother embodiment, the present disclosure provides a fusion polypeptidethat is at least 85%, at least 90%, at least 91%, at least 92%, at least93%, at least 94%, at least 95%, at least 96%, at least 96%, at least97%, at least 98%, at least 99% or 100% identical to SEQ ID NO: 53.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 54.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 55.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 56.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 57.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 58.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 59.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 60.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 61.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 62.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 63.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 64.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 65.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 66.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 67.

In another embodiment, the present disclosure provides a fusionpolypeptide that is at least 85%, at least 90%, at least 91%, at least92%, at least 93%, at least 94%, at least 95%, at least 96%, at least96%, at least 97%, at least 98%, at least 99% or 100% identical to SEQID NO: 68.

In one embodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of beta Klotho protein with signal peptide fused(directly or indirectly via a linker) to FGF-19 or an active fragmentthereof. In some embodiments, the fusion further comprises a modified Fcfragment having decreased affinity for Fc-gamma-receptor and/orincreased serum half-life. In another embodiment, the present disclosureprovides a fusion polypeptide comprising a sKlotho of beta Klothoprotein without signal peptide fused (directly or indirectly via alinker) to FGF-19 or an active fragment thereof. In another embodiment,the present disclosure provides a fusion polypeptide comprising asKlotho of beta Klotho protein with signal peptide fused (directly orindirectly via a linker) to FGF-21 or an active fragment thereof. Inanother embodiment, the present disclosure provides a fusion polypeptidecomprising a sKlotho of beta Klotho protein without signal peptide fused(directly or indirectly via a linker) to FGF-21 or an active fragmentthereof.

The disclosure provides nucleic acid sequences encoding any of theKlotho fusion polypeptides described herein and host cells containingthe nucleic acids. In some embodiments, the fusion further comprises amodified Fc fragment having decreased affinity for Fc-gamma-receptorand/or increased serum half-life.

The disclosure also provides composition having any of the Klotho fusionpolypeptides contemplated herein. The compositions of the disclosure canfurther include heparin. In some embodiments, the fusion furthercomprises a modified Fc fragment having decreased affinity forFc-gamma-receptor and/or increased serum half-life.

The disclosure also provides a method for treating or preventing anage-related condition in an individual. An individual (e.g., human) isadministered a therapeutically effective dose of a pharmaceuticalcomposition containing a Klotho fusion polypeptide, having at least oneextracellular subdomain of a Klotho protein (e.g., alpha Klotho protein)and a fibroblast growth factor or an active fragment thereof so as totreat or prevent the age-related condition. In some embodiments, thefusion further comprises a modified Fc fragment having decreasedaffinity for Fc-gamma-receptor and/or increased serum half-life. Inparticular, the disclosure provides a method of treating or preventingmuscle wasting comprising administering to an individual (e.g., human)an therapeutically effective amount of a fusion polypeptide having atleast one extracellular subdomain of an alpha Klotho protein and afibroblast growth factor (or an active fragment thereof).

Additionally, the disclosure provides a method for treating orpreventing a metabolic disorder in an individual. An individual isadministered a therapeutically effective dose of a pharmaceuticalcomposition containing a fusion polypeptide of the disclosure, having atleast one extracellular subdomain of a Klotho protein and a fibroblastgrowth factor (or an active fragment thereof) so as to treat themetabolic disorder. In some embodiments, the fusion further comprises amodified Fc fragment having decreased affinity for Fc-gamma-receptorand/or increased serum half-life. In particular, a fusion polypeptide ofthe disclosure having at least one extracellular subdomain of abeta-Klotho protein and a fibroblast growth factor 21 is useful fortreating a metabolic disorder.

Klotho-FGF23 fusion polypeptides of the disclosure can be used fortreating or preventing hyperphosphatemia or calcinosis in an individual.In some embodiments, the fusion further comprises a modified Fc fragmenthaving decreased affinity for Fc-gamma-receptor and/or increased serumhalf-life. A pharmacologically effective dose of a pharmaceuticalcomposition containing the Klotho fusion polypeptide of the disclosure,having at least one extracellular subdomain of a Klotho protein and afibroblast growth factor, is administered to treat or preventhyperphosphatemia or calcinosis. In particular, a Klotho fusionpolypeptide of the disclosure having at least one extracellularsubdomain of an alpha Klotho protein and a fibroblast growth factor 23is useful for treating hyperphosphatemia or calcinosis.

Klotho-FGF23 fusion polypeptides of the disclosure can be used fortreating or preventing chronic renal disease or chronic renal failure inan individual. In some embodiments, the fusion further comprises amodified Fc fragment having decreased affinity for Fe-gamma-receptorand/or increased serum half-life. A therapeutically effective dose of apharmaceutical composition containing the Klotho fusion polypeptide ofthe disclosure, having at least one extracellular subdomain of a Klothoprotein (e.g., alpha Klotho protein) and a fibroblast growth factor, isadministered to treat or prevent chronic renal disease or chronic renalfailure.

Klotho-FGF23 fusion polypeptides of the disclosure can be used fortreating or preventing cancer (e.g., breast cancer) in an individual. Insome embodiments, the fusion further comprises a modified Fc fragmenthaving decreased affinity for Fc-gamma-receptor and/or increased serumhalf-life. A therapeutically effective dose of a pharmaceuticalcomposition containing the Klotho fusion polypeptide of the disclosure,having at least one extracellular subdomain of a Klotho protein (e.g.,alpha Klotho protein) and a fibroblast growth factor, is administered totreat or prevent cancer or breast cancer.

The present disclosure provides fusion polypeptides comprising at leastone extracellular subdomain of Klotho protein and a FGF or an activefragment thereof for use in medicine. In some embodiments, the fusionfurther comprises a modified Fc fragment having decreased affinity forFe-gamma-receptor and/or increased serum half-life. In one embodiment,the present disclosure provides fusion polypeptides comprising at leastone extracellular subdomain of Klotho protein and a FGF or an activefragment thereof for use in treating or preventing muscle atrophy. Thepresent disclosure also provides a method of treating or preventing anage related condition (e.g., muscle atrophy) comprising administering toan individual in need thereof a therapeutically effective dose of apharmaceutical composition comprising a soluble Klotho protein.

The disclosure futhermore provides the above described peptides andfusion polypeptides or pharmaceutical compositions comprising saidpeptides for use in therapy, as a medicament or for use in the treatmentof a pathological disorder, for example age-related condition, metabolicdisorder, hyperphosphatemia or calcinosis, chronic renal disease orchronic renal failure or to prevent cancer or breast cancer, in anindividual. Additonally, the disclosure further provides use of apolypeptide, nucleic acid or pharmaceutical composition of the inventionin the manifacture of a medicament for the treatment of a pathologicaldisorder, particularly for the treatment of the above mentioneddisorders, preferably age related conditions like muscle atrophy.

The disclosure also includes kits for treating or preventing anage-related disorder or metabolic disorder in an individual. The kitincludes instructions for use and a purified Klotho fusion polypeptidehaving at least one extracellular subdomain of a Klotho protein and afibroblast growth factor. In some embodiments, the fusion furthercomprises a modified Fc fragment having decreased affinity forFc-gamma-receptor and/or increased serum half-life.

The disclosure also provides a kit for producing a Klotho fusionpolypeptide of the disclosure. The kit of the disclosure includesinstructions for use and a nucleic acid encoding a Klotho fusionpolypeptide, having at least one extracellular subdomain of Klothoprotein and a fibroblast growth factor. In some embodiments, the fusionfurther comprises a modified Fc fragment having decreased affinity forFc-gamma-receptor and/or increased serum half-life.

In one embodiment of the disclosure, the fusion polypeptide comprises:(a) a polypeptide comprising a fibroblast growth factor, or afunctionally active variant or derivative (e.g., a variant comprising atleast one conservative amino acid substitution and/or one amino aciddeletion) thereof; and (b) a modified Fc fragment, or a functionallyactive variant or derivative (e.g., a variant comprising at least oneconservative amino acid substitution and/or one amino acid deletion)thereof, having decreased affinity for Fc-gamma-receptor and/orincreased serum half-life

In one embodiment of the disclosure, the polypeptide of (a) and thepolypeptide of (b) are connected by a polypeptide linker. The linker canbe repeated 1 to 30 times, or more.

In one embodiment of the disclosure, the polypeptide linker comprises anamino acid sequence selected from the group consisting of: SEQ ID NO:11, SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ IDNO: 16, SEQ ID NO: 17, and SEQ ID NO: 18.

In one embodiment of the disclosure, the polypeptide of (a) is connectedby a peptide bond to the N-terminus of said polypeptide linker, and thepolypeptide of (b) is connected by a peptide bond to the C-terminus ofsaid polypeptide linker.

In one embodiment of the disclosure, the fusion polypeptide furthercomprises a signal peptide.

In one embodiment of the disclosure, the signal peptide is the IgGsignal peptide.

In one embodiment of the disclosure, the fibroblast growth factor isfibroblast growth factor-23 or a fibroblast growth factor-23 variant(R179Q).

In one embodiment of the disclosure, the fibroblast growth factor isfibroblast growth factor-19 or fibroblast growth factor-21.

In one embodiment of the disclosure, fusion polypeptide comprises anamino acid sequence which is 95% or more identical to the amino acidsequence of SEQ ID NO: 51, or SEQ ID NO: 53.

In one embodiment of the disclosure, fusion polypeptide comprises theamino acid sequence of SEQ ID NO: 51, or SEQ ID NO: 53.

In one embodiment of the disclosure, fusion polypeptide comprisesFcLALA.

3. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates several different embodiments of the Klotho fusionpolypeptides of the disclosure. The represented fusion polypeptidesinclude one or more Klotho extracellular subdomains operatively linkedto a fibroblast growth factor. Polypeptides containing one or moreKlotho extracellular subdomains include, for example, an extracellulardomain of Klotho (e.g., aa 1 to 982 of human Klotho), or an activefragment of Klotho.

FIG. 2 illustrates the amino acid and nucleic acid sequences of severalKlotho fusion polypeptides of the disclosure and components thereof(e.g., Klotho extracellular domain, FGF). Fusion proteins comprisingsKlotho, FGF23 and FcLALA (a modified Fc fragment having decreasedaffinity for Fc-gamma-receptor and/or increased serum half-life) aredescribed in SEQ ID NOs. 46, 47, 48, and 49. Fusion proteins comprisingFGF23 and FcLALA are described in SEQ ID NOs. 50, 51, 52 and 53.

FIGS. 3A-3C depict protein expression of an sKlotho-FGF23 fusionprotein. FIG. 3A shows that sKlotho-FGF23 fusion protein was detected inconditioned media by Western blotting with anti-FGF23 antibodies. FIG.3B shows that sKlotho-FGF23 fusion protein was detected in conditionedmedia by SDS-PAGE and Coomassie blue staining FIG. 3C shows a highlypurified sKlotho-FGF23-6× His fusion protein, analyzed by SDS-PAGE andCoomassie blue staining.

FIG. 4 illustrates the results of an Egr-1 luciferase assay comparingthe activation level of Egr-1 in cells treated with conditioned mediacontaining either a Klotho fusion polypeptide, a FGF 23 polypeptideonly, a soluble Klotho (sKlotho) polypeptide only, and a soluble Klothopolypeptide in combination with a FGF 23 polypeptide in the absence orpresence of heparin (20 μg/ml).

FIGS. 5A-5B depict the results of an Egr-1 luciferase assay comparingthe activation level of Egr-1 in cells treated with purified Klothofusion polypeptide, FGF 23 polypeptide, or soluble Klotho polypeptide inthe absence or presence of heparin. FIG. 5A shows an the results of anexperiment comparing the activation level of Egr-1 in cells treated withFGF 23 alone, sKlotho-His (10 nM or 20 nM) and a combination of FGF 23and sKlotho-His (10 nM or 20 nM) in the absence or presence of heparin(20 μg/ml). FIG. 5B shows Egr-1 luciferase reporter activity in cellstreated with sKlotho-FGF23-His fusion (0 nM, 0.6 nM, 1.21 nM, 2.41 nM,4.83 nM, 9.65 nM, and 19.3 nM).

FIGS. 6A-6B illustrate the effect of treatment with a purified sKlothofusion polypeptide on C2C12 muscle cells. FIG. 6A shows measurements ofmyotube diameter in C2C12 muscle cells treated with either IGF-1 (10nM), FGF2 (20 ng/ml), or a purified Klotho fusion polypeptide (20 nM),in the absence or presence of dexamethasone (100 μM). FIG. 6B shows thephosphorylation of signaling pathway proteins in C2C12 muscle cells byIGF-1 (10 nM), FGF2 (20 ng/ml), or a purified Klotho fusion polypeptide(20 nM), in the absence or presence of rapamycin (40 nM).

FIG. 7 shows activation of EGR-1-luc reporter gene bysKlotho-FGF23(R179Q)-FcLALA fusion proteins.

FIG. 8 shows the activation of EGR-1-luc reporter gene byFGF23(R179Q)-FcLALA proteins.

FIG. 9 shows the pharmacokinetic profile of FGF23(R179Q) vsFGF23(R179Q)-FcLALAv2.

FIGS. 10A and 10B show the in vivo efficacy of sKlotho-FGF23 fusion inenhancing muscle growth after dexamethasone-induced muscle atrophy.

FIG. 11. This figure shows activation of EGR-1-luc reporter gene byFGF23(R179Q)-FcLALA and Q156A, C206S, C244S and C206S/C244S mutants.

FIG. 12 shows protein qualities and dimerization of WT (wild-type),Q156A, C206S, C244S and C206S/C244S mutants of FGF23(R179Q)-FcLaLa.

4. DETAILED DESCRIPTION

The present disclosure is directed to methods, kits and compositions forpreventing or treating age-related conditions and metabolic disorders;and to the use of said compostions in therapy, as a medicament or foruse in the treatment of a pathological disorder. The fusion polypeptidesof the disclosure include a Klotho protein or active fragment thereof.In some embodiments, the fusion polypeptides of the disclosure include aKlotho protein or an active fragment thereof operatively linked to afibroblast growth factor polypeptide or active fragment thereof. In someembodiments, the fusion further comprises a modified Fc fragment withdecreased ability to bind FcRn and/or increased stability in serum. Inanother embodiment, the fusion polypeptide comprises a FGF (e.g., FGF23)and a modified Fc fragment with decreased ability to bind FcRn and/orincreased stability in serum.

The fusion proteins or sKlotho of the present disclosure are useful inthe treatment and prevention of a variety of age-related conditionsincluding sarcopenia, skin atrophy, muscle wasting, brain atrophy,atherosclerosis, arteriosclerosis, pulmonary emphysema, osteoporosis,osteoarthritis, immunologic incompetence, high blood pressure, dementia,Huntington's disease, Alzheimer's disease, cataracts, age-relatedmacular degeneration, prostate cancer, stroke, diminished lifeexpectancy, memory loss, wrinkles, impaired kidney function, andage-related hearing loss; and metabolic disorders including Type IIDiabetes, Metabolic Syndrome, hyperglycemia, and obesity.

The present disclosure is based at least in part on the finding thatdespite the physical constraints (e.g., large size of both the Klothoand FGF polypeptides) the Klotho-FGF fusion polypeptides are highlyeffective in activating an FGF receptor. This finding is unexpectedgiven that fusion of these two proteins would likely interfere with theheterodimerization and thus the activities of the proteins; e.g., thebinding domains of the proteins may be perturbed by the fusion or theproteins may be mis-oriented spatially if put together in a “cis”formation.

The fusion polypeptides described herein are advantageous because theyallow the administration of a single therapeutic protein that hasenhanced activity compared to Klotho or FGF administered alone ortogether as separate polypeptides. The use of Klotho and FGF as a singlefusion polypeptide rather than as two separate polypeptides (i.e., aKlotho polypeptide and a separate FGF polypeptide) is more effective atactivating the FGF receptor.

Definitions

“Klotho polypeptide”, “Klotho protein”, or “Klotho” as used herein,includes active fragments, derivatives, mimetics, variants andchemically modified compounds or hybrids thereof of wild-type “Klotho”.A Klotho active fragment has the ability to bind to an FGF polypeptide.Generally, a Klotho active polypeptide contains at least a Klothosubdomain (e.g., KL-D1 and KL-D2). Wild-type Klotho has the amino acidsequence as is found in nature. Example Klotho polypeptides suitable foruse with the present disclosure include alpha-Klotho (SEQ ID NO: 2) andbeta-Klotho (SEQ ID NO: 4). Nucleotide and amino acid sequences of thealpha-Klotho and beta-Klotho are found in the GenBank database atAccession No. NM_(—)004795; NP_(—)004786 and NM_(—)175737; NP_(—)783864,respectively. Klotho polypeptides include those described in U.S. Pat.No. 6,579,850, the content of which is herein incorporated by referencein its entirety. The Klotho polypeptides include those from otherspecies besides humans, including alpha-Klotho from mouse(NP_(—)038851), rat (NP_(—)112626), rabbit (NP_(—)001075692) andbeta-Klotho from mouse (NP_(—)112457). Species predicted to havealpha-Klotho include chimpanzee (XP_(—)522655), macaque(XP_(—)001101127), horse (XP_(—)001495662), cow (XP_(—)001252500),platypus (XP_(—)001510981), and chicken (XP_(—)417105). Speciespredicted to have beta-Klotho include chimpanzee (XP_(—)526550), macaque(XP_(—)001091413), horse (XP_(—)001495248), dog (XP_(—)536257), rat(XP_(—)001078178), platypus (XP_(—)001512722), and chicken(XP_(—)423224). The Klotho polypeptides have an amino acid sequence thatis substantially identical to the amino acid sequence of SEQ ID NO: 2 orSEQ ID NO: 4; i.e., at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%,98%, 99% or more identical at the amino acid sequences of SEQ ID NO: 2or SEQ ID NO: 4, or active fragment thereof.

“Fusion polypeptide” or “fusion protein”, as used herein, shall mean apolypeptide comprising two or more different polypeptides or activefragments thereof that are not naturally present in the samepolypeptide. In some embodiments, the two or more different polypeptidesare operatively linked together covalently, e.g., chemically linked orfused in frame by a peptide bond. As used herein a “Klotho fusionpolypeptide” is a fusion polypeptide which includes an amino acidsequence from a Klotho polypeptide or active fragment thereof. A fusionpolypeptide can comprise, as non-limiting examples, Klotho (e.g.,sKlotho), FGF (e.g., FG23), and (optionally) a modified Fc fragment(e.g., a modified Fc fragment with decreased binding affinity toFC-gamma-receptor and/or increased serum half-life). Examples of thistype of fusion polypeptide are presented in SEQ ID NOs. 46 to 49. Inanother embodiment, the fusion proteins comprise FGF (e.g., FGF23) and amodified Fc (e.g., FcLALA). Fusion proteins comprising FGF23 and FcLALAare described in SEQ ID NOs. 50, 51, 52 and 53. FcLALA is a Fc fragmentwith a LALA mutation (L234A, L235A), which triggers ADCC with loweredefficiency, and binds and activates human complement weakly. Hessell etal. 2007 Nature 449:101-104.

“Fibroblast growth factor” and “FGF” are used interchangeably herein andshall refer to polypeptides that regulate cell proliferation, migration,differentiation, homeostasis, tissue repair and response to injury in ananimal, including a human subject. FGFs have the ability to bind to afibroblast growth factor receptor and regulate its activity, includingautophosphorylation of FGFR, phosphorylation of FRS2 (FGF receptorsubstrate 2) and ERK1/2 (extracellular signal-regulated protein kinase1/2), and activating Egr-1 (early growth response-1). The term “FGF”includes active fragments, derivatives, mimetics, variants andchemically modified compounds or hybrids thereof of wild-type “FGF”,e.g., as known in the art and as described in U.S. Pat. No. 7,223,563and U.S. Pat. No. 7,259,248, the contents of which are incorporated byreference in their entirety. Wild-type FGF has an amino acid sequence asis found in nature. Example fibroblast growth factors suitable for usewith the present disclosure include fibroblast growth factor-19 (FGF 19;SEQ ID NO: 31), fibroblast growth factor-21 (FGF21; SEQ ID NO: 33), andfibroblast growth factor-23 (FGF23; SEQ ID NO: 35). The FGF polypeptidesinclude those from other species besides humans, including murine FGFs.Generally, FGF polypeptides have an amino acid sequence that issubstantially identical to the amino acid sequence of SEQ ID NO: 31, SEQID NO: 33 or SEQ ID NO: 35; i.e., having an amino acid sequence is whichis at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more or100% identical to the amino acid sequences of SEQ ID NO: 31 SEQ ID NO:33 or SEQ ID NO: 35, or active fragments thereof. Additionalnon-limiting examples of FGF, particularly FGF23, are provided at aa1002-1228 of SEQ ID NO: 47; aa 1002-1228 of SEQ ID NO: 49; aa 1-251 ofSEQ ID NO: 51, and aa 1-251 of SEQ ID NO: 53; and sequences which are atleast 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or more or 100%identical to these sequences. Nucleotides encoding these sequences areprovided in SEQ ID NOs: 46, 48, 50 and 52.

The term “FGF”, includes active fragments of the full-lengthpolypeptide. Active FGF fragments that are able to bind to theircorresponding FGF receptors are known in the art and also contemplatedfor use in the present disclosure. One skilled in the art wouldappreciate, based on the sequences disclosed herein, that overlappingfragments of the FGFs can be generated using standard recombinanttechnology, for example, that described in Sambrook et al. (1989,Molecular Cloning: A Laboratory Manual, Cold Spring Harbor LaboratoryPress, New York) and Ausubel et al. (1997, Current Protocols inMolecular Biology, Green & Wiley, New York). One skilled in the artwould appreciate, based on the disclosure presented herein, that thebiological activity of FGF fragments could be tested by methods wellknown in the art and described herein, including binding to the FGFreceptor. Similarly, cell culture models which possess the necessary FGFsignal transduction machinery (i.e. FGF receptor) may be transfectedwith FGF fragments and subsequently tested for alterations in FGFsignaling, relative to wild type FGF.

FGFs are grouped into seven subfamilies based on the homology of the FGFcore homology domain (approximately 120 amino acids long), which isflanked by N- and C-terminal sequences that are highly variable in bothlength and primary sequence, particularly among different FGFsubfamilies (Goetz et al., Molecular and Cellular Biology, 2007, Vol.27, 3417-3428). An FGF active polypeptide generally contains at least anFGF core homology domain. In some embodiments, an FGF active polypeptidemay contain, in addition to an FGF core homology domain, flankingsequences which may confer additional specificity in binding FGFreceptors. FGF19, FGF21, and FGF23 are grouped in the FGF 19 subfamilybecause the core region of these ligands share high sequence identityrelative to other FGFs (FGF19 v. FGF21: 38% identity; FGF19 v. FGF23:36% identity). FGF19 subfamily members act analogously to signalingmolecules of the endocrine system and regulate diverse physiologicalprocesses uncommon to classical FGFs (e.g., FGF19: energy and bile acidhomeostasis; FGF21: glucose and lipid metabolism; and FGF 23: phosphateand vitamin D homeostasis).

“Fibroblast growth factor receptor” and “FGFR” as used herein refer toany one of FGFRs 1-4 known in the art, or splice variants thereof (e.g.,FGFR1c). Example fibroblast growth factor receptors suitable for usewith the present disclosure include fibroblast growth factor receptor-19(e.g., FGFR4-beta Klotho), fibroblast growth factor receptor-21 (e.g.,FGFR1c-alpha Klotho), and fibroblast growth factor receptor-23 (e.g.,FGFR1c-alpha Klotho, FGFR3-alpha Klotho, FGFR4-alpha Klotho).

“Extracellular domain”, as used herein, refers to the fragment of atransmembrane protein existing outside of a cell (e.g., not includingthe intracellular or transmembrane region). The “extracellular domain ofthe Klotho protein”, “soluble Klotho”, or “sKlotho” (e.g., SEQ ID NO: 7;SEQ ID NO: 39), refers to an extracellular domain of the Klothopolypeptide that is capable of binding a fibroblast growth factor,and/or capable of enabling the binding of a fibroblast growth factor toa fibroblast growth factor receptor by binding to the fibroblast growthfactor. The Klotho extracellular domain corresponds to amino acidresidues 28-982 of the full length alpha Klotho sequence (SEQ ID NO: 2)and to amino acid residues 52-997 of the full length beta Klothosequence (SEQ ID NO: 4).

“Extracellular subdomain of Klotho protein” and “extracellular subdomainof Klotho protein” are used interchangeably herein and shall refer to aregion in the extracellular domain of the Klotho polypeptide that iscapable of binding a fibroblast growth factor, and/or is capable ofenabling the binding of a fibroblast growth factor to a fibroblastgrowth factor receptor by binding to the fibroblast growth factor. Invarious embodiments, the fusion comprises a polypeptide comprising atleast one extracellular subdomain of a Klotho protein; a polypeptidecomprising a fibroblast growth factor; and, optionally, a modified Fcfragment having decreased affinity for Fc-gamma-receptor and/orincreased serum half-life. The Klotho extracellular domain has twohomologous subdomains that are repeated, i.e., KL-D1 (SEQ ID NO: 5) andKL-D2 (SEQ ID NO: 6). KL-D1 and KL-D2 correspond respectively to aminoacid residues 58-506 and 517-953 of the full length alpha Klothopolypeptide (SEQ ID NO: 2) and respectively to amino acid residues77-508 and 571-967 of the full length beta Klotho polypeptide (SEQ IDNO: 4) and are suitable for use with the present disclosure. Generally,a polypeptide that contains at least one Klotho subdomain is a Klothoactive polypeptide. The Klotho extracellular subdomain for use with thepolypeptide of the disclosure may be an alpha Klotho or beta KlothoKL-D1 domain with an amino acid sequence that is substantially identicalto the amino acid sequence of SEQ ID NO: 5 or SEQ ID NO: 37,respectively. Further, the Klotho KL-D1 domain may have an amino acidsequence that is at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%,99% or more identical to the amino acid sequence of SEQ ID NO: 5 or SEQID NO: 37. The Klotho extracellular subdomain may also be an alpha orbeta Klotho polypeptide KL-D2 domain that is substantially identical tothe amino acid sequence of SEQ ID NO: 6 or SEQ ID NO: 38, respectively.In a further embodiment, the KL-D2 domain has an amino acid sequencethat is at least at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%,99% or more identical to the amino acid sequence of SEQ ID NO: 6 or SEQID NO: 38. In some embodiments, the fusion comprises at least twoextracellular subdomains of the Klotho protein (e.g., KL-D1 and KL-D2;KL-D1 and KL-D1 in tandem repeats; KL-D2 and KL-D2 in tandem repeats,etc.).

“Modified Fc fragment”, as used herein, shall mean an Fc fragment of anantibody comprising a modified sequence. The Fc fragment is a portion ofan antibody comprising the CH2, CH3 and part of the hinge region. Themodified Fc fragment can be derived from, for example, IgG1, IgG2, IgG3,or IgG4. FcLALA is a modified Fc fragment with a LALA mutation (L234A,L235A), which triggers ADCC with lowered efficiency, and binds andactivates human complement weakly. Hessell et al. 2007 Nature449:101-104. Additional modifications to the Fc fragment are describedin, for example, U.S. Pat. No. 7,217,798. For example, in variousmodified Fc fragments: (a) amino acid residue 250 is glutamic acid andamino acid residue 428 is phenylalanine; or (b) amino acid residue 250is glutamine and amino acid residue 428 is phenylalanine; or (c) aminoacid residue 250 is glutamine and amino acid residue 428 is leucine. Insome embodiments, amino acid residues 250 and 428 differ from theresidues present in an unmodified Fc-fusion protein by amino acidresidue 250 being glutamic acid or glutamine and amino acid residue 428being leucine or phenylalanine, and wherein amino acid residues arenumbered by the EU numbering system, as described in U.S. Pat. No.7,217,798. In some embodiments, the modified Fc-fusion protein has ahigher affinity for FcRn at pH 6.0 than at pH 8.0. Preferably, themodified Fc fragment has decreased affinity to FcRn and/or increasedserum half-life. Non-limiting examples of modified Fc fragments includethat at aa (amino acids) 1234-1459 of SEQ ID NO: 47; aa 1234 to 1450 ofSEQ ID NO: 49; aa 257 to 482 of SEQ ID NO: 51; and aa 257 to 473 of SEQID NO: 53; and sequences which are at least 70%, 75%, 80%, 85%, 90%,95%, 96%, 97%, 98%, 99% or more or 100% identical to these sequences.Nucleotides encoding these sequences are provided in SEQ ID NOs: 46, 48,50 and 52.

“Signal peptide”, as used herein, shall mean a peptide chain (3-60 aminoacids long) that directs the post-translational transport of a proteinto the endoplasmic reticulum and may be cleaved off. Example signalpeptides suitable for use with the present disclosure include the Klothosignal peptide (SEQ ID NO: 19) and the IgG signal peptide (SEQ ID NO:20). Note that upon secretion and cleavage by the producer cell line,the signal peptide (e.g., of the peptides corresponding to SEQ ID NO: 19and SEQ ID NO: 20) is cleaved off. Thus, after secretion and cleavage ofthe signal peptide by the producer cell lines, the peptide of SEQ ID NO:19 would generate the peptide of SEQ ID NO: 41.

“Linker”, as used herein, shall mean a functional group (e.g., chemicalor polypeptide) that covalently attaches two or more polypeptides ornucleic acids so that they are connected with one another. As usedherein, a “peptide linker” refers to one or more amino acids used tocouple two proteins together (e.g., to couple the extracellular domainof Klotho and fibroblast growth factor-23). Peptide linkers suitable foruse with the present disclosure include, but are not limited to,polypeptides with amino acid sequences represented by SEQ ID NO: 8, SEQID NO: 9, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 13,SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO: 16, SEQ ID NO: 17 and SEQ IDNO: 18. A polypeptide linker can comprise at least 1 and up to about 30repeats of any of these amino acid sequences.

“Operatively linked”, as used herein, shall mean the linking of two ormore biomolecules so that the biological functions, activities, and/orstructure associated with the biomolecules are at least retained. Inreference to polypeptides, the term means that the linking of two ormore polypeptides results in a fusion polypeptide that retains at leastsome of the respective individual activities of each polypeptidecomponent. The two or more polypeptides may be linked directly or via alinker. In reference to nucleic acids, the term means that a firstpolynucleotide is positioned adjacent to a second polynucleotide thatdirects transcription of the first polynucleotide when appropriatemolecules (e.g., transcriptional activator proteins) are bound to thesecond polynucleotide.

“Specifically binds”, as used herein, shall refer to the ability of afirst molecule to bind to a target molecule out of many, different typesof molecules to which it may be exposed because of the ability of thefirst molecule to adopt a particular structure conducive to formingnon-covalent interactions between itself and the other target molecule.The first molecule binds to the target forming a stable complex whilethere is substantially less recognition, contact, or complex formationof the first molecule with any other non-specific molecules.

“Polypeptide variant” or “protein variant”, as used herein, refers topolypeptides in which one or more amino acids have been substituted bydifferent amino acids from a reference sequence. It is well understoodin the art that some amino acids may be substituted by others withbroadly similar properties without changing the nature of the activityof the polypeptide (conservative substitutions) as describedhereinafter. These terms also encompass polypeptides in which one ormore amino acids have been added or deleted, or replaced with differentamino acids, e.g., protein isoforms. An example variant of fibroblastgrowth factor-23 suitable for use with the present disclosure is thefibroblast growth factor-23 variant (R179Q).

“Pharmaceutical composition”, as used herein, shall mean a compositioncontaining a compound (e.g., a fusion polypeptide of the disclosure)that may be administered to treat or prevent a disease or disorder in anindividual.

“Individual” or “subject”, as used herein, shall refer to a mammal,including, but not limited to, a human or non-human mammal, such as abovine, equine, canine, ovine, or feline.

“Treat”, as used herein, shall mean decrease, suppress, attenuate,diminish, arrest, or stabilize the development or progression of adisease. In the context of the disclosure, the administration of thepolypeptides of the disclosure may be used to treat age-relatedconditions, including sarcopenia, skin atrophy, muscle wasting, brainatrophy, atherosclerosis, arteriosclerosis, pulmonary emphysema,osteoporosis, osteoarthritis, immunologic incompetence, high bloodpressure, dementia, Huntington's disease, Alzheimer's disease,cataracts, age-related macular degeneration, prostate cancer, stroke,diminished life expectancy, memory loss, wrinkles, impaired kidneyfunction, and age-related hearing loss; and metabolic disorders,including Type II Diabetes, Metabolic Syndrome, hyperglycemia, andobesity.

“Prevent”, as used herein, shall refer to a decrease in the occurrenceof a disorder or decrease in the risk of acquiring a disorder or itsassociated symptoms in a subject. In the context of the disclosure, theadministration of the polypeptides of the disclosure may be used toprevent age-related conditions, including sarcopenia, skin atrophy,muscle wasting, brain atrophy, atherosclerosis, arteriosclerosis,pulmonary emphysema, osteoporosis, osteoarthritis, immunologicincompetence, high blood pressure, dementia, Huntington's disease,Alzheimer's disease, cataracts, age-related macular degeneration,prostate cancer, stroke, diminished life expectancy, memory loss,wrinkles, impaired kidney function, and age-related hearing loss; andmetabolic disorders, including Type II Diabetes, Metabolic Syndrome,hyperglycemia, and obesity. The prevention may be complete, e.g., thetotal absence of an age-related condition or metabolic disorder. Theprevention may also be partial, such that the likelihood of theoccurrence of the age-related condition or metabolic disorder in asubject is less likely to occur than had the subject not received thepresent disclosure.

“Disease”, as used herein, shall mean any condition or disorder thatdamages or interferes with the normal function of a cell, tissue, ororgan.

“Age-related condition”, as used herein, shall mean any disease ordisorder whose incidence in a population or severity in an individualcorrelates with the progression of age. In one embodiment, theage-related condition is a disease or disorder whose incidence is atleast 1.5 fold higher among human individuals greater than 60 years ofage relative to human individuals between the ages of 30-40 and in aselected population of greater than 100,000 individuals. Age-relatedconditions relevant to the present disclosure include, but are notlimited to, sarcopenia, skin atrophy, muscle wasting, brain atrophy,atherosclerosis, arteriosclerosis, pulmonary emphysema, osteoporosis,osteoarthritis, immunologic incompetence, high blood pressure, dementia,Huntington's disease, Alzheimer's disease, cataracts, age-relatedmacular degeneration, prostate cancer, stroke, diminished lifeexpectancy, memory loss, wrinkles, impaired kidney function, andage-related hearing loss.

“Metabolic disorder”, as used herein, shall mean any disease or disorderthat damages or interferes with normal function in a cell, tissue, ororgan by affecting the production of energy in cells or the accumulationof toxins in a cell, tissue, organ, or individual. Metabolic disordersrelevant to the present disclosure include, but are not limited to, TypeII Diabetes, Metabolic Syndrome, hyperglycemia, and obesity.

An “effective dose” or “effective amount” is an amount sufficient toeffect a beneficial or desired clinical result. In the context of thedisclosure, it is an amount of a Klotho fusion polypeptide or sKlothoeffective to produce the intended pharmacological, therapeutic orpreventive result. A therapeutically effective dose results in theprevention or amelioration of the disorder or one or more symptoms ofthe disorder, (e.g., an age-related condition or metabolic disorder).Therapeutically effective doses will vary depending upon the subject anddisease condition being treated, the weight and age of the subject, theseverity of the disease condition, the manner of administration and thelike which can be readily be determined by one of ordinary skill in theart.

“Klotho nucleic acid molecule”, as used herein is a gene encoding aKlotho protein. An example human Klotho gene is provided at GenBankAccession No. NM_(—)004795 (SEQ ID NO: 1). Additional non-limitingexamples of Klotho are provided at aa 1-982 of SEQ ID NO: 47 and aa1-982 of SEQ ID NO: 49; and sequences which are at least 70%, 75%, 80%,85%, 90%, 95%, 96%, 97%, 98%, 99% or more or 100% identical to thesesequences.

“Fragment”, as used herein, refers to a portion of a polypeptide ornucleic acid molecule. This portion contains, preferably, at least 10%,20%, 30%, 40%, 50%, 60%, 70%, 80%, 90% or more of the entire length ofthe reference nucleic acid molecule or polypeptide. A fragment maycontain 10, 20, 30, 40, 50, 60, 70, 80, 90, or 100, 200, 300, 400, 500,600, 700, 800, 900, 1000 or up to 3000 nucleotides or amino acids.

The term “substantially identical” refers to a polypeptide or nucleicacid molecule exhibiting at least 50% identity to a reference amino acidsequence (for example, any one of the amino acid sequences describedherein) or nucleic acid sequence (for example, any one of the nucleicacid sequences described herein). Preferably, such a sequence is atleast 60%, 70%, 75%, 80% or 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%,98%, 99% or more identical at the amino acid level or nucleic acid tothe sequence used for comparison.

The present disclosure is directed to methods, kits and compositions forpreventing or treating age-related conditions and metabolic disorders;and to the use of said compostions in therapy, as a medicament or foruse in the treatment of a pathological disorder. In some embodiments,the disclosure provides a fusion polypeptide having at least oneextracellular subdomain of a Klotho protein. In some embodiments, thefusion polypeptides further comprise a fibroblast growth factor or anactive fragment thereof. In some embodiments, the fusion furthercomprises a modified Fc fragment having decreased affinity forFc-gamma-receptorand/or increased serum half-life. In other embodiments,the fusion comprises an FGF (e.g., FGF19, FGF21, FGF23 or FGF23 variantR179Q) fused to a modified Fc (e.g., FcLALA). FcLALA is a Fc fragmentwith a LALA mutation (L234A, L235A), which triggers ADCC with loweredefficiency, and binds and activates human complement weakly. The Klothoextracellular domain may be derived from either the alpha or beta Klothoisoforms. Further, although the FGF component of the Klotho fusionpolypeptide is described primarily with reference to fibroblast growthfactor-19, fibroblast growth factor-21 and fibroblast growth factor-23,it is contemplated that any of the twenty-three known FGFs or an activefragment thereof can be used in practicing the disclosure.

The extracellular domain of the Klotho protein can include one or bothof the KL-D1 and KL-D2 domains of a Klotho protein. In some embodiments,the Klotho fusion polypeptide has at least two extracellular subdomainsof a Klotho protein. For example, the at least two extracellularsubdomains can be at least two KL-D1 domains in tandem repeats, at leasttwo KL-D2 domains in tandem repeats, or at least one KL-D1 domain and atleast one KL-D2 domain.

The extracellular subdomain of a Klotho protein and the fibroblastgrowth factor (or an active fragment thereof) can be operatively linkedto one another in a variety of orientations and manners. For example,the extracellular subdomain of the Klotho protein can be operativelylinked to the N-terminus of the fibroblast growth factor oralternatively the fibroblast growth factor can be operatively linked tothe N-terminus of the at least one extracellular subdomain of the Klothoprotein.

The fusion polypeptide of the disclosure may include one or both of theKlotho extracellular domains, i.e., KL-D1 (SEQ ID NO: 5) and KL-D2 (SEQID NO: 6). KL-D1 and KL-D2 correspond respectively to amino acidresidues 58-506 and 517-953 of the full length alpha Klotho polypeptide(SEQ ID NO: 2) and to amino acid residues 77-508 and 571-967 of the fulllength beta Klotho polypeptide (SEQ ID NO: 4) and are suitable for usewith the present disclosure. The Klotho fusion polypeptide may have aKL-D1 domain of an alpha Klotho polypeptide having an amino acidsequence that is substantially identical to the amino acid sequence ofSEQ ID NO: 5 or of a beta Klotho polypeptide having an amino acidsequence that is substantially identical to the amino acid sequence ofSEQ ID NO: 37. Specifically, the Klotho fusion polypeptide may have anamino acid sequence that is at least at least 70%, 75%, 80%, 85%, 90%,95%, 96%, 97%, 98%, 99% or more identical to SEQ ID NO: 5 or SEQ ID NO:37. The Klotho fusion polypeptide may have a KL-D2 domain of an alphaKlotho polypeptide with an amino acid sequence that is substantiallyidentical to the amino acid sequence of SEQ ID NO: 6 or of a beta Klothopolypeptide having an amino acid sequence that is substantiallyidentical to the amino acid sequence of SEQ ID NO: 38. Specifically, theKlotho fusion polypeptide may have an amino acid sequence that is atleast at least 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99% or moreidentical to SEQ ID NO: 6 or SEQ ID NO: 38, respectively.

In some embodiments, the Klotho fusion polypeptide of the disclosure issoluble and is capable of binding to an FGF receptor.

The Klotho fusion polypeptides of the disclosure can contain apolypeptide linker which connects the polypeptide having at least oneextracellular subdomain of a Klotho protein and the fibroblast growthfactor and the (optional) modified Fc fragment. Suitable linkers arewell known in the art and generally contain several Gly and several Serresidues, e.g., (Gly₄ Ser)₃ (SEQ ID NO: 11), Gly₄ Ser polypeptide (SEQID NO: 12), Gly (SEQ ID NO: 13), Gly Gly (SEQ ID NO: 14), Gly Ser (SEQID NO: 15), Gly₂ Ser (SEQ ID NO: 16), Ala (SEQ ID NO: 17), and Ala Ala(SEQ ID NO: 18). In some embodiments, the linker will have at least 2and up to about 30 repeats of an amino acid sequence represented by anyone of SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQID NO: 16, SEQ ID NO: 17, or SEQ ID NO: 18.

When a polypeptide linker is present in the Klotho fusion polypeptide ofthe disclosure, the polypeptide having at least one extracellularsubdomain of a Klotho protein may be connected by a peptide bond to theN-terminus of the linker polypeptide with the FGF connected by a peptidebond to the C-terminus of the polypeptide linker. Alternatively, the FGFmay be connected by a peptide bond to the N-terminus of the linkerpolypeptide with the polypeptide having at least one extracellularsubdomain of Klotho connected by a peptide bond to the C-terminus of thepolypeptide linker. A chemical linker can also be used to link the twopolypeptides.

The Klotho fusion polypeptide of the disclosure may include a signalpeptide. Example signal peptides for use with the Klotho fusionpolypeptide include, but are not limited to the Klotho signal peptide(SEQ ID NO: 8) and the IgG signal peptide (SEQ ID NO: 9).

In some embodiments, the disclosure provides a fusion between a FGF(e.g., FGF19, FGF21, FGF23, or FGF23 variant R179Q) and a modified Fc(e.g., FcLALA). The fusion can also optionally comprise linkers betweenthe FGF and Fc portions. The fusion can also optionally comprise asignal peptide. In various embodiments, the disclosure encompassesnucleic acids encoding these fusion polypeptides, vectors comprisingthese nucleic acids, and host cells containing these nucleic acids.

4.1. Klotho and Fibroblast Growth Factor Polypeptides

The Klotho fusion polypeptides of the disclosure are expected to exhibitbiological activities comparable to FGF in nature, such as binding to anFGF receptor and inducing the phosphorylation of an FGF receptor, FRS2(FGF receptor substrate 2) and ERK1/2 (extracellular signal-regulatedprotein kinase 1/2) and activating Egr-1 (early growth response-1) gene.FGF is a secreted peptide growth factor that binds the FGF receptor. Theamino acid and nucleic acid sequences of FGF are readily available tothose of skill in the art. For example, example nucleotide sequences forFGF19, FGF21, and FGF23 can be found in the GenBank database atAccession numbers: NM_(—)005117, NM_(—)019113, and NM_(—)020638,respectively, and herein as SEQ ID NOs: 30, 32, and 34, respectively.Example amino sequences for FGF19, FGF21, and FGF23 can be found in theGenBank database at Accession numbers: NP_(—)005108, NP_(—)061986, andNP_(—)065689, respectively, and herein as SEQ ID NOs: 31, 35, and 35,respectively. Additionally, FGF may include one or more alterationswhich aid in the expression of the protein, e.g., the FGF23 (R179Q)variant (SEQ ID NO: 36).

The Klotho protein is a 130 kDa single pass type I transmembrane proteinwith an extracellular domain and a short cytoplasmic domain. The aminoacid and nucleic acid sequences of Klotho are readily available to thoseof skill in the art. For example, example nucleotide sequences foralpha-Klotho and beta-Klotho can be found in the GenBank database atAccession numbers: NM_(—)004795 and NM_(—)175737, respectively, andherein as SEQ ID NOs: 7 and 8, respectively. Example amino acidsequences for alpha-Klotho and beta-Klotho can be found in the GenBankdatabase at Accession numbers: NP_(—)004786 and NP_(—)783864,respectively, and herein as SEQ ID NOs: 2 and 4, respectively.

The Klotho fusion polypeptide of the disclosure can bind to a fibroblastgrowth factor receptor and has an alpha-Klotho or beta-Klothoextracellular domain operatively linked to either fibroblast growthfactor-19 (SEQ ID NO: 31), fibroblast growth factor-21 (SEQ ID NO: 33),fibroblast growth factor-23 (SEQ ID NO: 35), or variants thereof (whichinclude fibroblast growth factor-23 variant (R179Q) (SEQ ID NO: 36)).

Specifically, the Klotho fusion polypeptide of the disclosure mayinclude an alpha-Klotho (SEQ ID NO: 2) which is operatively coupled tofibroblast growth factor-23 (SEQ ID NO: 35) or fibroblast growthfactor-23 variant (R179Q) (SEQ ID NO: 36). Additionally, the Klothofusion polypeptide of the disclosure may have beta-Klotho (SEQ ID NO:4), which is operatively coupled to fibroblast growth factor-19 (SEQ IDNO: 31). The Klotho fusion polypeptide of the disclosure may include abeta-Klotho (SEQ ID NO: 4), which is operatively coupled to fibroblastgrowth factor-21 (SEQ ID NO: 33).

The disclosure includes homologs of the various Klotho and FGF genes andproteins encoded by those genes. A “homolog,” in reference to a generefers to a nucleotide sequence that is substantially identical over atleast part of the gene or to its complementary strand or a part thereof,provided that the nucleotide sequence encodes a protein that hassubstantially the same activity/function as the protein encoded by thegene which it is a homolog of. Homologs of the genes described hereincan be identified by percent identity between amino acid or nucleotidesequences for putative homologs and the sequences for the genes orproteins encoded by them (e.g., nucleotide sequences for genes encodingKlotho and FGF or their complementary strands). Percent identity may bedetermined, for example, by visual inspection or by using variouscomputer programs known in the art or as described herein. Sequenceidentity is typically measured using sequence analysis software (forexample, Sequence Analysis Software Package of the Genetics ComputerGroup, University of Wisconsin Biotechnology Center, 1710 UniversityAvenue, Madison, Wis. 53705, BLAST, BESTFIT, GAP, or PILEUP/PRETTYBOXprograms). Such software matches identical or similar sequences byassigning degrees of homology to various substitutions, deletions,and/or other modifications. Conservative amino acid substitutionstypically include substitutions within the following groups:

-   glycine and alanine;-   valine, isoleucine and leucine;-   aspartic acid, glutamic acid, asparagine and glutamine;-   serine and threonine;-   lysine and arginine; and-   phenylalanine and tyrosine.    Thus, mutating a glycine to alanine would be a conservative amino    acid substititon, as would mutating an alanine to a glycine;    mutating a valine to an isoleucine or leucine would be a    conservative amino acid substation, as would replacing an isoleucine    with valine or leucine, as would replacing leucine with valine or    isoleucine, etc. The disclosure provides variants of all the amino    acid sequences disclosed herein with at least one conservative amino    acid substitution.    In an example approach to determining the degree of identity, a    BLAST program may be used, with a probability score between e⁻³ and    e⁻¹⁰⁰ indicating a closely related sequence.

In one embodiment, the present disclosure provides a fusion polypeptideof SEQ ID NO: 19.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 20.

In one embodiment, the present disclosure provides a fusion polypeptideof SEQ ID NO: 40.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 41, or a variant thereof comprising at leastone conservative amino acid substition.

In one embodiment, the present disclosure provides a fusion polypeptideof SEQ ID NO: 46.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 47, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 48.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 49, or a variant thereof comprising at leastone conservative amino acid substition.

In one embodiment, the present disclosure provides a fusion polypeptideof SEQ ID NO: 50.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 51, or a variant thereof comprising at leastone conservative amino acid substition.

In one embodiment, the present disclosure provides a fusion polypeptideof SEQ ID NO: 52.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 53, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 54, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 55, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 56, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 57, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 58, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 59, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 60, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 61, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 62, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 63, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 64, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 65, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 66, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 67, or a variant thereof comprising at leastone conservative amino acid substition.

In another embodiment, the present disclosure provides a fusionpolypeptide of SEQ ID NO: 68, or a variant thereof comprising at leastone conservative amino acid substition.

As used herein, the terms “homology” and “homologous” are not limited todesignate proteins having a theoretical common genetic ancestor, butincludes proteins which may be genetically unrelated that have,nonetheless, evolved to perform similar functions and/or have similarstructures. Functional homology to the various proteins described hereinalso encompasses proteins that have an activity of the correspondingprotein of which it is a homolog. For proteins to have functionalhomology, it is not required that they have significant identity intheir amino acid sequences, but, rather, proteins having functionalhomology are so defined by having similar or identical activities. Forexample, with respect to a Klotho molecule, the polypeptide should havethe functional characteristics of binding to an FGF polypeptide andenable the binding of the FGF to an FGFR. With respect to an FGFmolecule, the polypeptide should have the functional characteristics ofbinding to an FGFR and causing the activation of FGFR (e.g.,phosphorylation). Assays for assessing FGF binding to the FGF receptorand/or activation of the FGF signaling pathway are known in the art anddescribed herein (See Example 2). Assays for assessing Klotho activityare also known in the art and described herein (e.g., binding to a FGFpolypeptide). Proteins with structural homology are defined as havinganalogous tertiary (or quaternary) structure and do not necessarilyrequire amino acid identity or nucleic acid identity for the genesencoding them. In certain circumstances, structural homologs may includeproteins which maintain structural homology only at the active site orbinding site of the protein.

In addition to structural and functional homology, the presentdisclosure further encompasses proteins having amino acid identity tothe various Klotho and FGF amino acid sequences described herein. Todetermine the percent identity/homology of two amino acid sequences, thesequences are aligned for optimal comparison purposes (e.g., gaps can beintroduced in the amino acid sequence of one protein for optimalalignment with the amino acid sequence of another protein). The aminoacid residues at corresponding amino acid positions are then compared.When a position in one sequence is occupied by the same amino acidresidue as the corresponding position in the other, then the moleculesare identical at that position. The percent identity between the twosequences is a function of the number of identical positions shared bythe sequences (i.e., % identity=# of identical positions/total # ofpositions multiplied by 100).

The amino acid sequences of molecules of the disclosure described hereinhave an amino acid sequence which is at least about 60%, 70%, 80%, 90%,95%, 96%, 97%, 98%, 99% or more identical or homologous to an amino acidsequence described herein.

The nucleic acid sequences of molecules of the disclosure describedherein have a nucleotide sequence which hybridizes to or is at leastabout 60%, 70%, 80%, 90%, 95%, 96%, 97%, 98%, 99% or more identical orhomologous to a nucleotide sequence described herein.

Nucleic acid molecules appropriate for use in the fusion polypeptides ofthe disclosure may have a Klotho or FGF nucleotide sequence whichhybridizes under stringent conditions to the complement of a nucleicacid molecule encoding Klotho or FGF, respectively. As used herein, theterm “hybridizes under stringent conditions” is intended to describeconditions for hybridization and washing under which nucleotidesequences at least about 70%, 80%, 85%, 90% or more homologous to eachother typically remain hybridized to each other. Such stringentconditions are known to those skilled in the art and can be found inAusubel et al. Current Protocols in Molecular Biology, WileyInterscience, New York (2001), 6.3.1-6.3.6. A specific, non-limitingexample of stringent hybridization conditions are hybridization in 6×sodium chloride/sodium citrate (SSC) at about 45° C., followed by one ormore washes in 0.2×SSC, 0.1% SDS at 50-65° C.

4.2. Klotho-FGF Fusion Polypeptides of the Disclosure

In some embodiments of the disclosure, a Klotho fusion polypeptide has apolypeptide chain having a first polypeptide sequence of a Klothopolypeptide or an active fragment thereof and a second polypeptidesequence encoding FGF or an active fragment thereof. In someembodiments, the fusion further comprises a modified Fc fragment havingdecreased affinity for Fc-gamma-receptor and/or increased serumhalf-life.

The disclosure includes fusion polypeptides which are at least about 95%or more homologous to an amino acid sequence presented in SEQ ‘ID NO:19-28. The amino acid sequence of SEQ ID NO: 19 encodes a Klotho fusionpolypeptide having a Klotho extracellular domain N-terminally linked tothe FGF23 (R179Q) variant (SEQ ID NO: 36). The amino acid sequence ofSEQ ID NO: 20 encodes a Klotho fusion polypeptide having an IgG signalpeptide N-terminally linked to a Klotho extracellular domain lacking asignal peptide N-terminally linked to the FGF23 (R179Q) variant. Theamino acid sequence of SEQ ID NO: 21 encodes a Klotho fusion polypeptidehaving a KL-D1 extracellular subdomain N-terminally linked to the FGF23(R179Q) variant. The amino acid sequence of SEQ ID NO: 22 encodes aKlotho fusion polypeptide having a KL-D2 extracellular subdomainN-terminally linked to the FGF23 (R179Q) variant. The amino acidsequence of SEQ ID NO: 23 encodes a Klotho fusion polypeptide having twoKL-D1 extracellular subdomains N-terminally linked to the FGF23 (R179Q)variant. The amino acid sequence of SEQ ID NO: 24 encodes a Klothofusion polypeptide having two KL-D2 extracellular subdomainsN-terminally linked to the FGF23 (R179Q) variant. The amino acidsequence of SEQ ID NO: 25 encodes a Klotho fusion polypeptide having theFGF23 (R179Q) variant N-terminally linked to a Klotho extracellulardomain. The amino acid sequence of SEQ ID NO: 26 encodes a Klotho fusionpolypeptide having the FGF23 (R179Q) variant N-terminally linked to aKL-D1 extracellular subdomain. The amino acid sequence of SEQ ID NO: 27encodes a Klotho fusion polypeptide having the FGF23 (R179Q) variantN-terminally linked to a KL-D2 extracellular subdomain. The amino acidsequence of SEQ ID NO: 28 encodes a Klotho fusion polypeptide having theFGF23 (R179Q) variant N-terminally linked to two KL-D1 extracellularsubdomains. The amino acid sequence of SEQ ID NO: 29 encodes a Klothofusion polypeptide having the FGF23 (R179Q) variant N-terminally linkedto two KL-D2 extracellular subdomains. In some embodiments, the fusionfurther comprises a modified Fc fragment having decreased affinity forFc-gamma-receptor and/or increased serum half-life.

The Klotho fusion polypeptide of the disclosure may include an aminoacid sequence which is at least about 95% identical to the amino acidsequence set forth in SEQ ID NO: 7. The amino acid sequence of SEQ IDNO: 7 encodes a Klotho extracellular domain lacking a signal peptide. Insome embodiments, the fusion further comprises a modified Fc fragmenthaving decreased affinity for Fc-gamma-receptor and/or increased serumhalf-life.

The subject fusion proteins are described herein and can be made usingmethods known in the art. For example, the fusion polypeptides of thedisclosure may be constructed as described in U.S. Pat. No. 6,194,177.The use of Klotho polypeptides is described in U.S. Pat. No. 6,579,850.The use of FGF nucleic acid molecules is described in U.S. Pat. No.7,223,563.

In some embodiments, a nucleic acid molecule encoding the Klotho iscloned by PCR and ligated, in frame, with a nucleic acid moleculeencoding FGF. In some embodiments, the fusion further comprises amodified Fc fragment having decreased affinity for Fc-gamma-receptorand/or increased serum half-life. The nucleic acid encoding the fusionpolypeptide is operatively linked to a promoter to allow for expression.The nucleic acid molecule encoding the fusion polypeptide issubsequently transfected into a host cell for expression. The sequenceof the final construct can be confirmed by sequencing.

When preparing the fusion proteins of the present disclosure, a nucleicacid molecule encoding an extracellular subdomain of Klotho will befused in frame to the nucleic acid molecule encoding FGF and the(optional) nucleic acid encoding the modified Fc fragment. Expression ofthe resulting nucleic acid molecule results in the extracellularsubdomain of Klotho being fused N-terminal in relation to the FGFpolypeptide. Fusions are also possible in which the extracellularsubdomain of Klotho is fused C-terminal in relation to the FGFpolypeptide. Methods for making fusion proteins are well known in theart.

The fusion polypeptides of the disclosure have at least two polypeptidesthat are covalently linked, in which one polypeptide comes from oneprotein sequence or domain, e.g., Klotho, and the other polypeptidecomes from another protein sequence or domain, e.g., FGF. In someembodiments, the fusion further comprises a modified Fc fragment havingdecreased affinity for Fc-gamma-receptor and/or increased serumhalf-life. In another embodiment, the disclosure comprises a FGF fusedto a modified Fc fragment. Klotho and/or FGF and/or the (optional)modified Fc fragment, of the fusion polypeptides of the disclosure, canbe joined by methods well known to those of skill in the art. Thesemethods include both chemical and recombinant means.

Nucleic acids encoding the domains to be incorporated into the fusionpolypeptides of the disclosure can be obtained using routine techniquesin the field of recombinant genetics. Basic texts disclosing the generalmethods of use in this disclosure include Sambrook and Russell,Molecular Cloning, A Laboratory Manual (3rd ed. 2001); Kriegler, GeneTransfer and Expression: A Laboratory Manual (1990); and CurrentProtocols in Molecular Biology (Ausubel et al., eds., 1994-1999). Innucleic acids encoding a Klotho fusion polypeptide of the disclosure,the nucleic acid sequence encoding alpha-Klotho or beta-Klotho,represented by SEQ ID NO: 1 and SEQ ID NO: 3, respectively, may be used.In nucleic acids encoding a Klotho fusion polypeptide, the nucleic acidsequence encoding FGF19, FGF21, or FGF23, represented by SEQ ID NO: 30,SEQ ID NO: 32 and SEQ ID NO: 34, respectively, may be used. Nucleic acidsequences of molecules of the disclosure described herein comprise anucleotide sequence which hybridizes to or is at least about 60%, 70%,80%, 90%, 95%, 96%, 97%, 98%, 99% or more identical or homologous to SEQID NO: 1, SEQ ID NO: 3, SEQ ID NO: 30, SEQ ID NO: 32, or SEQ ID NO: 34.

Nucleic acid sequences that encode the various components of the fusion[Klotho, and/or FGF peptide and/or the (optional) modified Fe fragment]can be obtained using any of a variety of methods. For example, thenucleic acid sequences encoding the polypeptides may be cloned from cDNAand genomic DNA libraries by hybridization with probes, or isolatedusing amplification techniques with oligonucleotide primers. Morecommonly, amplification techniques are used to amplify and isolate theKlotho and FGF sequences using a DNA or RNA template (see, e.g.,Dieffenfach & Dveksler, PCR Primers: A Laboratory Manual (1995)).Alternatively, overlapping oligonucleotides can be producedsynthetically and joined to produce one or more of the domains. Nucleicacids encoding Klotho or FGF can also be isolated from expressionlibraries using antibodies as probes.

According to the present disclosure, the various components of thefusion [Klotho, and/or, FGF and/or the (optional) modified Fc fragment]can be linked either directly or via a covalent linker, including aminoacid linkers, such as a polyglycine linker, or another type of chemicallinker, including, carbohydrate linkers, lipid linkers, fatty acidlinkers, polyether linkers, such as PEG, etc. (See for example,Hermanson, Bioconjugate techniques (1996)). The polypeptides forming thefusion/fusion polypeptide are typically linked C-terminus to N-terminus,although they can also be linked C-terminus to C-terminus, N-terminus toN-terminus, or N-terminus to C-terminus. One or more polypeptide domainsmay be inserted at an internal location within a fusion polypeptide ofthe disclosure. The polypeptides of the fusion protein can be in anyorder. The fusion polypeptides may be produced by covalently linking achain of amino acids from one protein sequence, e.g., an extracellularsubdomain of Klotho, to a chain of amino acids from another proteinsequence, e.g., FGF, by preparing a recombinant polynucleotidecontiguously encoding the fusion protein. The different chains of aminoacids in a fusion protein may be directly spliced together or may beindirectly spliced together via a chemical linking group or an aminoacid linking group. The amino acid linking group can be about 200 aminoacids or more in length, or generally 1 to 100 amino acids. In someembodiments, proline residues are incorporated into the linker toprevent the formation of significant secondary structural elements bythe linker. Linkers can often be flexible amino acid subsequences thatare synthesized as part of a recombinant fusion protein. Such flexiblelinkers are known to persons of skill in the art.

According to the present disclosure, the amino acid sequences of thefusion [an extracellular subdomain of Klotho and/or the FGF and/or the(optional) modified Fc fragment] may be linked via a peptide linker.Example peptide linkers are well known in the art and described herein.For example, peptide linkers generally include several Gly and severalSer residues, such as: (Gly₄ Ser)₃ (SEQ ID NO: 11), Gly₄ Ser polypeptide(SEQ ID NO: 12), Gly (SEQ ID NO: 13), Gly Gly (SEQ ID NO: 14), Gly Ser(SEQ ID NO: 15), Gly₂ Ser (SEQ ID NO: 16), Ala (SEQ ID NO: 17), and AlaAla (SEQ ID NO: 18). Specifically, a peptide linker for use in a fusionprotein of the disclosure may act as a flexible hinge.

The signal sequence of Klotho or FGF may be excluded prior toincorporation of Klotho into a fusion protein of the disclosure. Thesignal sequence for Klotho or FGF of the fusion protein may be included,e.g., the polypeptide represented by SEQ ID NO: 19. However, suchsequences may also be omitted and replaced with the signal sequence of adifferent protein, e.g., the IgG signal sequence (SEQ ID NO: 9).Generally, the pharmaceutical compositions of the disclosure willcontain the mature form of Klotho and FGF.

Generally, introns are excluded from either one or both the Klotho orthe FGF moieties prior to incorporation into a fusion polypeptide.

The fusion polypeptides of the disclosure may include one or morepolymers covalently attached to one or more reactive amino acid sidechains. By way of example, not limitation, such polymers includepolyethylene glycol (PEG), which can be attached to one or more freecysteine sulthydryl residues, thereby blocking the formation ofdisulfide bonds and aggregation when the protein is exposed to oxidizingconditions. In addition, PEGylation of the fusion polypeptides of thedisclosure is expected to provide such improved properties as increasedhalf-life, solubility, and protease resistance. The fusion polypeptidesof the disclosure may alternatively be modified by the covalent additionof polymers to free amino groups such as the lysine epsilon or theN-terminal amino group. Particular specific cysteines and lysines forcovalent modification will be those not involved in receptor binding,heparin binding, or in proper protein folding. It will be apparent toone skilled in the art that the methods for assaying the biochemicaland/or biological activity of the fusion polypeptides may be employed inorder to determine if modification of a particular amino acid residueaffects the activity of the protein as desired. Other similar suitablemodifications are contemplated and known in the art.

The disclosure is also directed to the expression of a fusionpolypeptide that is at least about 95% or more homologous to an aminoacid sequence presented in SEQ ID NO: 19-28.

The present disclosure encompasses a fusion polypeptide comprising: (a)a polypeptide comprising at least one extracellular subdomain of aKlotho protein, or a functionally active variant or derivative thereof;(b) a polypeptide comprising a fibroblast growth factor, or afunctionally active variant or derivative thereof; and (c) a modified Fcfragment having decreased affinity for Fc-gamma-receptor and/orincreased serum half-life. By “a functionally active variant orderivative thereof” is meant a variant or derivative comprising alonger, shorter or altered amino acid sequence than the correspondingwild-type polypeptide, while retaining the biological activity. Thus “afunctionally active variant or derivative” of an extracellular subdomainof a Klotho protein or a fibroblast growth factor comprises fewer, more,or an altered amino acid sequence than a wild-type extracellularsubdomain of a Klotho protein or a fibroblast growth factor, but stillretains at least one biological activity of the wild-type polypeptidesequence. A functionally active variant or derivative of a polypeptidedisclosed herein can also comprise the same amino acid sequence of apolypeptide disclosed herein, but vary in post-translationalmodification (e.g., pegylation, methylation and/or glycosylation), orhave additional moieties or elements added to it. In variousembodiments, the variant or derivative of FGF23 comprises R179Q or doesnot.

In one embodiment, a functionally active variant or derivativepolypeptide includes an amino acid sequence at least about 60% identicalto a sequence disclosed herein (e.g., at least one extracellular domainof a Klotho protein or a fibroblast growth factor). Preferably, thepolypeptide is at least 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%,98%, 99% or more identical to a sequence disclosed herein.

As used herein, percent identity of two amino acid sequences (or of twonucleic acid sequences) is determined using the algorithm of Karlin andAltschul (PNAS USA 87:2264-2268, 1990), modified as in Karlin andAltschul, PNAS USA 90:5873-5877, 1993). Such an algorithm isincorporated into the NBLAST and XBLAST programs of Altschul et al. (J.Mol. Biol. 215:403-410, 1990). BLAST nucleotide searches are performedwith the NBLAST program, score=100, wordlength=12. BLAST proteinsearches are performed with the XBLAST program, score=50, wordlength=3.To obtain gapped alignment for comparison purposes GappedBLAST isutilized as described in Altschul et al. (Nucleic Acids Res.25:3389-3402, 1997). When utilizing BLAST and GappedBLAST programs thedefault parameters of the respective programs (e.g., XBLAST and NBLAST)are used to obtain nucleotide sequences homologous to a nucleic acidmolecule of the invention.

Identity or identical means amino acid sequence (or nucleic acidsequence) similarity and has an art recognized meaning. Sequences withidentity share identical or similar amino acids (or nucleic acids).Thus, a candidate sequence sharing 85% amino acid sequence identity witha reference sequence requires that, following alignment of the candidatesequence with the reference sequence, 85% of the amino acids in thecandidate sequence are identical to the corresponding amino acids in thereference sequence, and/or constitute conservative amino acid changes.

Functionally active variants of a polypeptide disclosed herein retainsubstantially the same functional activity of the original polypeptideor fragment. Naturally occurring functionally active variants such asallelic variants and species variants and non-naturally occurringfunctionally active variants are included in the invention and can beproduced by, for example, mutagenesis techniques or by direct synthesis.

A functionally active variant or derivative differs by about or atleast, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60 or more amino acidresidues from a polypeptide disclosed herein. Where this comparisonrequires alignment the sequences are aligned for maximum homology. Thesite of variation can occur anywhere in the polypeptide, as long asactivity substantially similar to a polypeptide disclosed herein.

Guidance concerning how to make variants and derivatives withphenotypically silent amino acid substitutions is provided in Bowie etal., Science, 247:1306-1310 (1990), which teaches that there are twomain strategies for studying the tolerance of an amino acid sequence tochange.

The first strategy exploits the tolerance of amino acid substitutions bynatural selection during the process of evolution. By comparing aminoacid sequences in different species, the amino acid positions which havebeen conserved between species can be identified. See e.g., FIG. 5.These conserved amino acids are likely important for protein function.In contrast, the amino acid positions in which substitutions have beentolerated by natural selection indicate positions which are not criticalfor protein function. Thus, positions tolerating amino acid substitutioncan be modified while still maintaining specific binding activity of thepolypeptide.

The second strategy uses genetic engineering to introduce amino acidchanges at specific positions of a cloned gene to identify regionscritical for protein function. For example, site-directed mutagenesis oralanine-scanning mutagenesis (the introduction of single alaninemutations at every residue in the molecule) can be used (Cunningham etal., Science, 244:1081-1085 (1989)).

Methods of introducing a mutation into amino acids of a protein is wellknown to those skilled in the art. See, e.g., Ausubel (ed.), CurrentProtocols in Molecular Biology, John Wiley and Sons, Inc. (1994); T.Maniatis, E. F. Fritsch and J. Sambrook, Molecular Cloning: A LaboratoryManual, Cold Spring Harbor laboratory, Cold Spring Harbor, N.Y. (1989)).Mutations can also be introduced using commercially available kits suchas “QuikChange.™. Site-Directed Mutagenesis Kit” (Stratagene). Thegeneration of a polypeptide functionally active variant or derivative toa polypeptide by replacing an amino acid that does not influence thefunction of a polypeptide can be accomplished by one skilled in the art.

A variant or derivative can have, for example, one or more conservativesubstitutions while still retaining at least one biological activity. Aconservative substitution is one in which an amino acid is substitutedfor another amino acid that has similar properties, such that oneskilled in the art of peptide chemistry would expect the secondarystructure and hydropathic nature of the polypeptide to be substantiallyunchanged. In general, the following groups of amino acids representconservative changes: (1) ala, pro, gly, glu, asp, gln, asn, ser, thr;(2) cys, ser, tyr, thr; (3) val, ile, leu, met, ala, phe; (4) lys, arg,his; and (5) phe, tyr, trp, his.

Particular example variants and derivatives include, without limitation,functionally active variants and derivatives of a polypeptide comprisingat least one extracellular subdomain of a Klotho protein, e.g., apolypeptide comprising at least about 100, 150, 200, 250, 300, 350, 375,400, or 425 contiguous amino acids of an extracellular domain of Klotho(e.g., SEQ ID NO: 5 or 6), with no more than about 1, 2, 3, 4, 5, 6, 7,8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45,50, 55, 60 or more amino acid residue differences from the wild-typesequence (as disclosed in SEQ ID NO: 5 or 6), while retaining at leastone biological activity of the wild-type polypeptide. For example, afunctionally active variant or derivative of a polypeptide comprising atleast one extracellular subdomain of a Klotho protein comprises apolypeptide comprising at least about 400 contiguous amino acids of SEQID NO: 5 or 6, with no more than about 100 amino acid residuedifferences. For example, a functionally active variant or derivative ofa polypeptide comprising at least one extracellular subdomain of aKlotho protein comprises a polypeptide comprising at least about 400contiguous amino acids of SEQ ID NO: 5 or 6, with no more than about 50amino acid residue differences. For example, a functionally activevariant or derivative of a polypeptide comprising at least oneextracellular subdomain of a Klotho protein comprises a polypeptidecomprising at least about 425 contiguous amino acids of SEQ ID NO: 5 or6, with no more than about 25 amino acid residue differences. Forexample, a functionally active variant or derivative of a polypeptidecomprising at least one extracellular subdomain of a Klotho proteincomprises a polypeptide comprising at least about 425 contiguous aminoacids of SEQ ID NO: 5 or 6, with no more than about 10 amino acidresidue differences. In another example, a functionally active variantor derivative of a polypeptide comprising at least one extracellularsubdomain of a Klotho protein comprises a polypeptide comprising atleast about 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650,700, 750, 800, 850, 900, 925, 950 or 982 contiguous amino acids of SEQID NO: 7, with no more than about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,13, 14, 15, 16, 17, 18, 19, 20, 25, 30, 35, 40, 45, 50, 55, 60, 70, 75,80, 85, 90, 95, 100, 110, 120, 140, 150, 160, 170, 180, 190, or 200amino acid residue differences from the wild-type sequence. For example,a functionally active variant or derivative of a polypeptide comprisingat least one extracellular subdomain of a Klotho protein comprises apolypeptide comprising at least about 500 contiguous amino acids of SEQID NO: 7, with no more than about 100 amino acid residue differences.For example, a functionally active variant or derivative of apolypeptide comprising at least one extracellular subdomain of a Klothoprotein comprises a polypeptide comprising at least about 600 contiguousamino acids of SEQ ID NO: 7, with no more than about 100 amino acidresidue differences. For example, a functionally active variant orderivative of a polypeptide comprising at least one extracellularsubdomain of a Klotho protein comprises a polypeptide comprising atleast about 700 contiguous amino acids of SEQ ID NO: 7, with no morethan about 100 amino acid residue differences. For example, afunctionally active variant or derivative of a polypeptide comprising atleast one extracellular subdomain of a Klotho protein comprises apolypeptide comprising at least about 800 contiguous amino acids of SEQID NO: 7, with no more than about 100 amino acid residue differences.For example, a functionally active variant or derivative of apolypeptide comprising at least one extracellular subdomain of a Klothoprotein comprises a polypeptide comprising at least about 900 contiguousamino acids of SEQ ID NO: 7, with no more than about 100 amino acidresidue differences. For example, a functionally active variant orderivative of a polypeptide comprising at least one extracellularsubdomain of a Klotho protein comprises a polypeptide comprising atleast about 900 contiguous amino acids of SEQ ID NO: 7, with no morethan about 50 amino acid residue differences.

Particular example variants and derivatives include, without limitation,functionally active variants and derivatives of a polypeptide comprisinga fibroblast growth factor, e.g., a polypeptide comprising at leastabout 100, 125, 150, 150, 175, 200, 225, or 250 contiguous amino acidsof a fibroblast growth factor, e.g., FGF19 (SEQ ID NO: 31), FGF21 (SEQID NO: 33), or FGF23 (SEQ ID NO: 35), with no more than about 1, 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 25, 30,35, 40, 45, 50, 55, 60 or more amino acid residue differences from thewild-type sequence (as disclosed in SEQ ID NOs: 31, 33 or 35), whileretaining at least one biological activity of the wild-type polypeptide.In various embodiments, the variant or derivative can comprise the R179Qvariation or not. For example, a functionally active variant orderivative of a polypeptide comprising a fibroblast growth factorcomprises a polypeptide comprising at least about 150 contiguous aminoacids of SEQ ID NOs: 31, 33 or 35, with no more than about 25 amino acidresidue differences. For example, a functionally active variant orderivative of a polypeptide comprising a fibroblast growth factorcomprises a polypeptide comprising at least about 175 contiguous aminoacids of SEQ ID NOs: 31, 33 or 35, with no more than about 25 amino acidresidue differences. For example, a functionally active variant orderivative of a polypeptide comprising a fibroblast growth factorcomprises a polypeptide comprising at least about 200 contiguous aminoacids of SEQ ID NOs: 31, 33 or 35, with no more than about 25 amino acidresidue differences. For example, a functionally active variant orderivative of a polypeptide comprising a fibroblast growth factorcomprises a polypeptide comprising at least about 225 contiguous aminoacids of SEQ ID NO: 35, with no more than about 50 amino acid residuedifferences. For example, a functionally active variant or derivative ofa polypeptide comprising a fibroblast growth factor comprises apolypeptide comprising at least about 225 contiguous amino acids of SEQID NO: 35, with no more than about 25 amino acid residue differences.

4.3. Expression of Fusion Polypeptides of the Disclosure

In order to express the fusion protein of the disclosure, DNA moleculesobtained by any of the methods described herein or those that are knownin the art, can be inserted into appropriate expression vectors bytechniques well known in the art. For example, a double stranded cDNAcan be cloned into a suitable vector by homopolymeric tailing or byrestriction enzyme linking involving the use of synthetic DNA linkers orby blunt-ended ligation. DNA ligases are usually used to ligate the DNAmolecules and undesirable joining can be avoided by treatment withalkaline phosphatase.

Therefore, the disclosure includes vectors (e.g., recombinant plasmidsand bacteriophages) that include nucleic acid molecules (e.g., genes orrecombinant nucleic acid molecules encoding genes) as described herein.The term “recombinant vector” includes a vector (e.g., plasmid, phage,phasmid, virus, cosmid, fosmid, or other purified nucleic acid vector)that has been altered, modified or engineered such that it containsgreater, fewer or different nucleic acid sequences than those includedin the native or natural nucleic acid molecule from which therecombinant vector was derived. For example, a recombinant vector mayinclude a nucleotide sequence encoding a Klotho-FGF23 fusion operativelylinked to regulatory sequences, e.g., promoter sequences, terminatorsequences and/or artificial ribosome binding sites (RBSs), as definedherein. Recombinant vectors which allow for expression of the genes ornucleic acids included in them are referred to as “expression vectors.”

For eukaryotic hosts, different transcriptional and translationalregulatory sequences may be employed, depending on the nature of thehost. They may be derived from viral sources, such as adenovirus, bovinepapilloma virus, Simian virus or the like, where the regulatory signalsare associated with a particular gene which has a high level ofexpression. Examples include, but are not limited to, the TK promoter ofthe Herpes virus, the SV40 early promoter, the yeast ga14 gene promoter,etc. Transcriptional initiation regulatory signals may be selected whichallow for repression or activation, so that expression of the genes canbe modulated.

In some of the molecules of the disclosure described herein, one or moreDNA molecules having a nucleotide sequence encoding one or morepolypeptide chains of a fusion polypeptide are operatively linked to oneor more regulatory sequences, which are capable of integrating thedesired DNA molecule into a host cell. Cells which have been stablytransformed by the introduced DNA can be selected, for example, byintroducing one or more markers which allow for selection of host cellswhich contain the expression vector. A selectable marker gene can eitherbe linked directly to a nucleic acid sequence to be expressed, or beintroduced into the same cell by co-transfection. Additional elementsmay also be needed for optimal synthesis of proteins described herein.It would be apparent to one of ordinary skill in the art whichadditional elements to use.

Factors of importance in selecting a particular plasmid or viral vectorinclude, but are not limited to, the ease with which recipient cellsthat contain the vector are recognized and selected from those recipientcells which do not contain the vector; the number of copies of thevector which are desired in a particular host; and whether it isdesirable to be able to “shuttle” the vector between host cells ofdifferent species.

Once the vector(s) is constructed to include a DNA sequence forexpression, it may be introduced into an appropriate host cell by one ormore of a variety of suitable methods that are known in the art,including but not limited to, for example, transformation, transfection,conjugation, protoplast fusion, electroporation, calciumphosphate-precipitation, direct microinjection, etc.

Host cells may either be prokaryotic or eukaryotic. Examples ofeukaryotic host cells include, for example, mammalian cells, such ashuman, monkey, mouse, and Chinese hamster ovary (CHO) cells. Such cellsfacilitate post-translational modifications of proteins, including, forexample, correct folding or glycosylation. Additionally, yeast cells canalso be used to express fusion polypeptides of the disclosure. Like mostmammalian cells, yeast cells also enable post-translationalmodifications of proteins, including, for example, glycosylation. Anumber of recombinant DNA strategies exist which utilize strong promotersequences and high copy number plasmids that can be utilized forproduction of proteins in yeast. Yeast transcription and translationmachinery can recognize leader sequences on cloned mammalian geneproducts, thereby enabling the secretion of peptides bearing leadersequences (i.e., pre-peptides). A particularmethod of high-yieldproduction of the fusion polypeptides of the disclosure is through theuse of dihydrofolate reductase (DHFR) amplification in DHFR-deficientCHO cells, by the use of successively increasing levels of methotrexateas described in U.S. Pat. No. 4,889,803. The polypeptide obtained may bein a glycosylated form.

After the introduction of one or more vector(s), host cells are usuallygrown in a selective medium, which selects for the growth ofvector-containing cells. Purification of the recombinant proteins can becarried out by any of the methods known in the art or described herein,for example, any conventional procedures involving extraction,precipitation, chromatography and electrophoresis. A furtherpurification procedure that may be used for purifying proteins isaffinity chromatography using monoclonal antibodies which bind a targetprotein. Generally, crude preparations containing a recombinant proteinare passed through a column on which a suitable monoclonal antibody isimmobilized. The protein usually binds to the column via the specificantibody while the impurities pass through. After washing the column,the protein is eluted from the gel by changing pH or ionic strength, forexample.

4.4. Assays for Assessing Fusion Polypeptide Activity

Assays described herein (See Example 2) and those known in the art canbe used for detecting Klotho or FGF activity of the fusion polypeptidesof the disclosure. Suitable activity assays include receptor bindingassays, cellular proliferation assays and cell signaling assays. Forexample, a binding assay which may be used for determining whether afusion polypeptide has Klotho or FGF activity includes, assaying thebinding of a fusion polypeptide to an FGF receptor. FGF receptor bindingassays include, but are not limited to, both competitive andnon-competitive assay. For example, FGF receptor binding can be detectedby contacting cells expressing an FGF receptor with a labeled FGF (forexample, radio-active label) and increasing concentrations of anunlabeled Klotho-FGF fusion polypeptide. The two ligands that competefor binding to the same receptor are added to a reaction mixturecontaining the cell. The cells are subsequently washed and labeled FGFis measured. A decrease in the amount of the labeled FGF to its receptorin the presence of the unlabeled fusion polypeptide is indicative ofbinding of the Klotho-FGF fusion polypeptide to the receptor.Alternatively, the Klotho-FGF fusion polypeptide may be labeled anddirect binding of the fusion polypeptide to the cell is detected.

Klotho or FGF activity can also be measured by determining whether thefusion polypeptide induces a cellular response. For example, in someembodiments, an assay for detecting the biological activity of aKlotho-FGF fusion polypeptide involves contacting cells which express anFGF receptor with a fusion polypeptide, assaying a cellular responsesuch as, for example, cell proliferation or Egr-1 activation, myotubediameter in C2C12 cells, and comparing the cellular response in thepresence and absence of the fusion polypeptide. An increase in thecellular response in the presence of the fusion polypeptide complexrelative to the absence indicates that the fusion polypeptide hasbiological activity. Also, an increase in a downstream signaling eventfrom the receptor can also be measured as indicia of biological activity(e.g., phosphorylation of FGFR, FRS2, ERK1/2, p70S6K etc.).

4.5 Pharmaceutical Compositions and Methods of Treatment

The disclosure also pertains to pharmaceutical compositions containingone or more fusion polypeptides of the disclosure and a pharmaceuticallyacceptable diluent or carrier. The pharmaceutical compositions canfurther include a pharmaceutically effective dose of heparin. Suchpharmaceutical compositions may be included in a kit or container. Suchkit or container may be packaged with instructions pertaining to theextended in vivo half-life or the in vitro shelf life of the fusionpolypeptides. Optionally associated with such kit or container(s) can bea notice in the form prescribed by a governmental agency regulating themanufacture, use or sale of pharmaceuticals or biological products,which notice reflects approval by the agency of manufacture, use or salefor human administration. Such compositions may be used in methods oftreating, preventing, or ameliorating a disease or a disease symptom(e.g., age-related condition or metabolic disorder) in a patient,preferably a mammal and most preferably a human, by administering thepharmaceutical composition to the patient.

In general, a therapeutically effective amount of a pharmaceuticalcomposition of the disclosure is from about 0.0001 mg/kg to 0.001 mg/kg;0.001 mg/kg to about 10 mg/kg body weight or from about 0.02 mg/kg toabout 5 mg/kg body weight. Commonly, a therapeutically effective amountof a fusion polypeptide is from about 0.001 mg to about 0.01 mg, about0.01 mg to about 100 mg, or from about 100 mg to about 1000 mg, forexample. Preferably, a therapeutically effective amount of a fusionpolypeptide is from about 0.001 mg/kg to 2mg/kg.

The optimal pharmaceutical formulations for a fusion polypeptide can bedetermined by one or ordinary skilled in the art depending upon theroute of administration and desired dosage. (See, for example,Remington's Pharmaceutical Sciences, 18th Ed. (1990), Mack PublishingCo., Easton, Pa., the entire disclosure of which is hereby incorporatedby reference).

The fusion polypeptides of the disclosure may be administered as apharmaceutical composition that may be in the form of a solid, liquid orgas (aerosol). Typical routes of administration may include, withoutlimitation, oral, topical, parenteral, sublingual, rectal, vaginal,intradermal and intranasal. Parenteral administration includessubcutaneous injections, intravenous, intramuscular, intraperitoneal,intrapleural, intrasternal injection or infusion techniques. Preferably,the compositions are administered parenterally. More preferably, thecompositions are administered intravenously. Pharmaceutical compositionsof the disclosure can be formulated so as to allow a polypeptide of thedisclosure to be bioavailable upon administration of the composition toa subject. Compositions can take the form of one or more dosage units,where, for example, a tablet can be a single dosage unit, and acontainer of a polypeptide of the disclosure in aerosol form can hold aplurality of dosage units.

Materials used in preparing the pharmaceutical compositions can benon-toxic in the amounts used. It will be evident to those of ordinaryskill in the art that the optimal dosage of the active ingredient(s) inthe pharmaceutical composition will depend on a variety of factors.Relevant factors include, without limitation, the type of subject (e.g.,human), the overall health of the subject, the type of age-relatedcondition or metabolic disorder the subject in need of treatment of, theuse of the composition as part of a multi-drug regimen, the particularform of the polypeptide of the disclosure, the manner of administration,and the composition employed.

The pharmaceutically acceptable carrier or vehicle may be particulate,so that the compositions are, for example, in tablet or powder form. Thecarrier(s) can be liquid, with the compositions being, for example, anoral syrup or injectable liquid. In addition, the carrier(s) can begaseous, so as to provide an aerosol composition useful in, e.g.,inhalatory administration.

The term “carrier” refers to a diluent, adjuvant or excipient, withwhich a polypeptide of the disclosure is administered. Suchpharmaceutical carriers can be liquids, such as water and oils,including those of petroleum, animal, vegetable or synthetic origin,such as peanut oil, soybean oil, mineral oil, sesame oil and the like.The carriers can be saline, gum acacia, gelatin, starch paste, talc,keratin, colloidal silica, urea, and the like. In addition, auxiliary,stabilizing, thickening, lubricating and coloring agents can be used. Inone embodiment, when administered to a subject, the polypeptides of thedisclosure and pharmaceutically acceptable carriers are sterile. Wateris a particular carrier when the polypeptide of the disclosure isadministered intravenously. Saline solutions and aqueous dextrose andglycerol solutions can also be employed as liquid carriers, particularlyfor injectable solutions. Suitable pharmaceutical carriers also includeexcipients such as starch, glucose, lactose, sucrose, gelatin, malt,rice, flour, chalk, silica gel, sodium stearate, glycerol monostearate,talc, sodium chloride, dried skim milk, glycerol, propylene, glycol,water, ethanol and the like. The present compositions, if desired, canalso contain minor amounts of wetting or emulsifying agents, or pHbuffering agents.

The composition may be intended for oral administration, and if so, thecomposition is preferably in solid or liquid form, where semi-solid,semi-liquid, suspension and gel forms are included within the formsconsidered herein as either solid or liquid.

As a solid composition for oral administration, the composition can beformulated into a powder, granule, compressed tablet, pill, capsule,chewing gum, wafer or the like form. Such a solid composition typicallycontains one or more inert diluents. In addition, one or more of thefollowing can be present: binders such as ethyl cellulose,carboxymethylcellulose, microcrystalline cellulose, or gelatin;excipients such as starch, lactose or dextrins, disintegrating agentssuch as alginic acid, sodium alginate, Primogel, corn starch and thelike; lubricants such as magnesium stearate or Sterotex; glidants suchas colloidal silicon dioxide; sweetening agents such as sucrose orsaccharin, a flavoring agent such as peppermint, methyl salicylate ororange flavoring, and a coloring agent.

When the pharmaceutical composition is in the form of a capsule, e.g., agelatin capsule, it can contain, in addition to materials of the abovetype, a liquid carrier such as polyethylene glycol, cyclodextrin or afatty oil.

The pharmaceutical composition can be in the form of a liquid, e.g., anelixir, syrup, solution, emulsion or suspension. The liquid can beuseful for oral administration or for delivery by injection. Whenintended for oral administration, a composition can contain one or moreof a sweetening agent, preservatives, dye/colorant and flavour enhancer.In a composition for administration by injection, one or more of asurfactant, preservative, wetting agent, dispersing agent, suspendingagent, buffer, stabilizer and isotonic agent can also be included.

The liquid compositions of the disclosure, whether they are solutions,suspensions or other like form, can also include one or more of thefollowing: sterile diluents such as water for injection, salinesolution, preferably physiological saline, Ringer's solution, isotonicsodium chloride, fixed oils such as synthetic mono or digylcerides whichcan serve as the solvent or suspending medium, polyethylene glycols,glycerin, cyclodextrin, propylene glycol or other solvents;antibacterial agents such as benzyl alcohol or methyl paraben;antioxidants such as ascorbic acid or sodium bisulfite; chelating agentssuch as ethylenediaminetetraacetic acid; buffers such as acetates,citrates or phosphates and agents for the adjustment of tonicity such assodium chloride or dextrose. A parenteral composition can be enclosed inan ampoule, a disposable syringe or a multiple-dose vial made of glass,plastic or other material. Physiological saline is a particular specificadjuvant. An injectable composition is preferably sterile.

The pharmaceutical compositions contain an effective amount of acompound of the disclosure (e.g., fusion polypeptide) such that asuitable dosage will be obtained. The pharmaceutical compositions maycontain the known effective amount of the compounds as currentlyprescribed for their respective disorders.

The route of administration of the polypeptide of the disclosure used inthe prophylactic and/or therapeutic regimens which will be effective inthe prevention, treatment, and/or management of a age-related conditionor metabolic disorder can be based on the currently prescribed routes ofadministration for other therapeutics known in the art. The polypeptidesof the disclosure can be administered by any convenient route, forexample, by infusion or bolus injection, by absorption throughepithelial or mucocutaneous linings (e.g., oral mucosa, rectal andintestinal mucosa, etc.). Administration can be systemic or local.Various delivery systems are known, e.g., microparticles, microcapsules,capsules, etc., and may be useful for administering a polypeptide of thedisclosure. More than one polypeptides of the disclosure may beadministered to a subject. Methods of administration may include, butare not limited to, oral administration and parenteral administration;parenteral administration including, but not limited to, intradermal,intramuscular, intraperitoneal, intravenous, subcutaneous, intranasal,epidural, sublingual, intranasal, intracerebral, intraventricular,intrathecal, intravaginal, transdermal, rectally, by inhalation, ortopically to the ears, nose, eyes, or skin.

The polypeptides of the disclosure may be administered parenterally.Specifically, the polypeptides of the disclosure may be administeredintravenously.

Pulmonary administration can also be employed, e.g., by use of aninhaler or nebulizer, and formulation with an aerosolizing agent, or viaperfusion in a fluorocarbon or synthetic pulmonary surfactant. Thepolypeptides of the disclosure can also be formulated as a suppository,with traditional binders and carriers such as triglycerides.

The polypeptides of the disclosure can be delivered in a controlledrelease system. For example, a pump can be used (see Sefton, CRC Crit.Ref. Biomed. Eng. 1987, 14, 201; Buchwald et al., Surgery 1980, 88: 507;Saudek et al., i N. Engl. J. Med. 1989, 321: 574). Polymeric materialscan also be used for controlled release of the polypeptides of thedisclosure (see Medical Applications of Controlled Release, Langer andWise (eds.), CRC Pres., Boca Raton, Fla., 1974; Controlled DrugBioavailability, Drug Product Design and Performance, Smolen and Ball(eds.), Wiley, New York, 1984; Ranger and Peppas, J. Macromol. Sci. Rev.Macromol. Chem. 1983, 23, 61; see also Levy et al., Science 1985, 228,190; During et al., Ann. Neurol., 1989, 25, 351; Howard et al., J.Neurosurg., 1989, 71, 105). Specifically, a controlled-release systemcan be placed in proximity of the target of the polypeptides of thedisclosure, e.g., the brain, thus requiring only a fraction of thesystemic dose (see, e.g., Goodson, in Medical Applications of ControlledRelease, supra, vol. 2, 1984, pp. 115-138). Other controlled-releasesystems discussed in the review by Langer (Science 1990, 249, 1527-1533)can be used.

Polymeric materials used to achieve controlled or sustained release ofthe polypeptides of the disclosure are disclosed, e.g., in U.S. Pat. No.5,679,377; U.S. Pat. No. 5,916,597; U.S. Pat. No. 5,912,015; U.S. Pat.No. 5,989,463; U.S. Pat. No. 5,128,326; PCT Publication No. WO 99/15154;and PCT Publication No. WO 99/20253. Examples of polymers used insustained release formulations include, but are not limited to,poly(2-hydroxy ethyl methacrylate), poly(methyl methacrylate),poly(acrylic acid), poly(ethylene-co-vinyl acetate), poly(methacrylicacid), polyglycolides (PLG), polyanhydrides, poly(N-vinyl pyrrolidone),poly(vinyl alcohol), polyacrylamide, poly(ethylene glycol), polylactides(PLA), poly(lactide-co-glycolides) (PLGA), and polyorthoesters.Preferably, the polymer used in a sustained release formulation isinert, free of leachable impurities, stable on storage, sterile, andbiodegradable.

In general, a therapeutically effective amount of a pharmaceuticalcomposition of the disclosure is from about 0.0001 mg/kg to 0.001 mg/kg;0.001 mg/kg to about 10 mg/kg body weight or from about 0.02 mg/kg toabout 5 mg/kg body weight.

In other embodiments, the prophylactic and/or therapeutic regimeninvolves administering to a patient one or more doses of an effectiveamount of a polypeptide of the disclosure, wherein the dose of aneffective amount achieves a plasma level of at least 0.01 μg/mL to atleast 400 μg/mL of the polypeptide of the disclosure.

A prophylactic and/or therapeutic regimen may involve administering to apatient a plurality of doses of an effective amount of a polypeptide ofthe disclosure, wherein the plurality of doses maintains a plasma levelof at least 0.01 μg/mL, to 400 μg/mL of the polypeptide of thedisclosure. The prophylactic and/or therapeutic regimen may beadministered for at least 1 day, 1 month, 2 months, 3 months, 4 months,5 months, 6 months, 7 months, 8 months or 9 months.

The prophylactic and/or therapeutic regimen may involve administrationof a polypeptide of the disclosure in combination with one or moreadditional therapeutics. The recommended dosages of the one or moretherapeutics currently used for the prevention, treatment, and/ormanagement of an age-related condition or metabolic disorder can beobtained from any reference in the art including, but not limited to,Hardman et al., eds., Goodman & Gilman's The Pharmacological Basis OfBasis Of Therapeutics, 10th ed., McGraw-Hill, New York, 2001;Physician's Desk Reference (60^(th) ed., 2006), which is incorporatedherein by reference in its entirety.

The disclosure includes methods of treating disorders wherein agonisticactivity of Klotho protein and FGF are desirable. The disclosurefurthermore includes the use of the disclosed proteins, fusion proteins,nucleic acid molecules or pharmaceutical composition in therapy or asmedicament for the treatment of a pathological disorder whereinagonistic activity of Klotho protein and FGF are desirable. Examples ofsuch methods or uses of the disclosure include, but are not limited toage-related condition or metabolic disorders.

The disclosure includes methods for treating or preventing anage-related condition in an individual; and the use of the disclosedproteins, fusion proteins, nucleic acid molecules or pharmaceuticalcomposition in therapy or as medicament for treating or preventing anage-related condition in an individual. An individual in need oftreatment is administered a pharmacologically effective dose of apharmaceutical composition containing a Klotho fusion polypeptide,having at least one extracellular subdomain of a Klotho protein and afibroblast growth factor and an (optional) modified Fc fragment, so asto treat or prevent the age-related condition. In some embodiments, theKlotho fusion polypeptide is co-administered with a pharmacologicallyeffective dose of heparin. Age-related conditions include sarcopenia,skin atrophy, muscle wasting, brain atrophy, atherosclerosis,arteriosclerosis, pulmonary emphysema, osteoporosis, osteoarthritis,immunologic incompetence, high blood pressure, dementia, Huntington'sdisease, Alzheimer's disease, cataracts, age-related maculardegeneration, prostate cancer, stroke, diminished life expectancy,memory loss, wrinkles, impaired kidney function, and age-related hearingloss. In some embodiments, the Klotho fusion polypeptide contains atleast one extracellular domain of an alpha Klotho protein. In aparticular embodiment, a Klotho fusion protein containing at least oneextracellular domain of alpha Klotho protein and fibroblast growthfactor 23 is administered to an individual in need of treatment formuscle wasting.

The disclosure is also directed to a method for treating or preventing ametabolic disorder in an individual; and to the use of the disclosedproteins, fusion proteins, nucleic acid molecules or pharmaceuticalcomposition in therapy or as medicament for treating or preventingmetabolic disorder in an individual. An individual in need of treatmentis administered a pharmacologically effective dose of a pharmaceuticalcomposition containing a Klotho fusion polypeptide, having at least oneextracellular subdomain of a Klotho protein and a fibroblast growthfactor so as to treat the metabolic disorder, and an (optional) modifiedFc fragment having decreased binding to FcRn and/or increased serumhalf-life and/or stability. In some embodiments, the Klotho fusionpolypeptide is co-administered with a pharmacologically effective doseof heparin. The method may be used in the treatment or prevention ofType II Diabetes, Metabolic Syndrome, hyperglycemia, and obesity. In aparticular embodiment, a Klotho fusion protein containing at least oneextracellular domain of a beta-Klotho protein and fibroblast growthfactor 21 is administered to an individual in need of treatment for ametabolic disorder.

The disclosure also provides methods for treating or preventinghyperphosphatemia or calcinosis in an individual; and the use of thedisclosed proteins, fusion proteins, nucleic acid molecules orpharmaceutical composition in therapy or as medicament for treating orpreventing hyperphosphatemia or calcinosis in an individual. Anindividual in need of treatment is administered a pharmacologicallyeffective dose of a pharmaceutical composition containing a Klothofusion polypeptide, having at least one extracellular subdomain of aKlotho protein, a fibroblast growth factor and an (optional) modified Fcfragment so as to treat hyperphosphatemia or calcinosis. In someembodiments, the Klotho fusion polypeptide is co-administered with apharmacologically effective dose of heparin. In a particular embodiment,a Klotho fusion protein containing at least one extracellular domain ofan alpha Klotho protein and fibroblast growth factor 23 and an(optional) modified Fc fragment is administered to an individual in needof treatment for a hyperphosphatemia or calcinosis.

The disclosure is also directed to a method for treating or preventingchronic renal disease or chronic renal failure in an individual; and tothe use of the disclosed proteins, fusion proteins, nucleic acidmolecules or pharmaceutical composition in therapy or as medicament fortreating or preventing chronic renal disease or chronic renal failure inan individual. An individual in need of treatment is administered apharmacologically effective dose of a pharmaceutical compositioncontaining a Klotho fusion polypeptide, having at least oneextracellular subdomain of a Klotho protein, a fibroblast growth factorand an (optional) modified Fc fragment so as to treat chronic renaldisease or chronic renal failure. In some embodiments, the Klotho fusionpolypeptide is co-administered with a pharmacologically effective doseof heparin. In some embodiments, a Klotho fusion protein containing atleast one extracellular domain of an alpha Klotho protein isadministered to an individual in need of treatment for chronic renaldisease or chronic renal failure.

The disclosure also includes methods for treating or preventing cancerin an individual; and the use of the disclosed proteins, fusionproteins, nucleic acid molecules or pharmaceutical composition intherapy or as medicament for treating or preventing cancer in anindividual. An individual in need of treatment is administered apharmacologically effective dose of a pharmaceutical compositioncontaining a Klotho fusion polypeptide, having at least oneextracellular subdomain of a Klotho protein, a fibroblast growth factorand an (optional) modified Fc fragment so as to treat cancer. The methodmay be used in the treatment or prevention of breast cancer. In someembodiments, the Klotho fusion polypeptide is co-administered with apharmacologically effective dose of heparin. In some embodiments, aKlotho fusion protein containing at least one extracellular domain of analpha Klotho protein is administered to an individual in need oftreatment for cancer.

In methods of treating disorders by administering a pharmaceuticalcomposition containing a Klotho fusion polypeptide; or when usingpharmaceutical composition containing a Klotho fusion polypeptide intherapy, the Klotho fusion polypeptide and an (optional) modified Fcfragment has at least one extracellular subdomain of a Klotho proteinand a fibroblast growth factor. In a particular embodiment, the Klothofusion protein contains at least one extracellular domain of a betaKlotho protein and fibroblast growth factor 21.

In another embodiment, the fusion comprises a FGF (e.g., FGF19, FGF21,FGF23 or FGF23 variant) and a modified Fc fragment with decreasedbinding to FcRn and/or increased serum stability. This type of fusioncan be used in various diseases, as described above, or used to treat orprevent any FGF-related disease known in the art. The fusion can beadministered to an individual in need thereof.

The fusion polypeptide compositions can be administered according to anymethod of administration known to those of skill in the art anddescribed herein. Particular specific methods of administration includesubcutaneous or intravenous. Other effective modes of administration aredescribed herein.

4.6. Methods of Treatment and Assays for Assessing Efficacy

Methods or uses of the disclosure which provide administering the fusionpolypeptides described herein to an individual can be used to treat avariety of disorders including an age-related disorder or a metabolicdisorder. Without being limited by any particular theory, fusionpolypeptides may be used to treat disorders in which there isdysregulation of Klotho or FGF. Example disorders include metabolicdisorders and age-related disorders. For example, both FGF23 or Klothoknock-out mice display a variety of similar phenotypes including, lowphysical activity, growth retardation, muscle wasting, skin atrophy,atherosclerosis, short life spans, etc. (See Razzaque and Lanske, J. ofEndrocrinology, 194:1-10 (2007), which is herein incorporated byreference).

In particular, fusion polypeptides of the disclosure are particularlyuseful in the treatment of aging-related disorders, including musclewasting. Without being bound to theory, the ability of Klotho and FGF23to control mineral (e.g., phosphate and calcium) and vitamin Dhomeostasis may be the means by which these proteins modulate aging andmuscle atrophy.

On the other hand, fusion polypeptides of the disclosure may be used fortreating a metabolic disorder. For example, beta-Klotho and FGF19 havebeen shown to control bile acid homeostasis by regulating cholesterol7-α-hydroxylase (CYP7A1). A non-limiting example of bile homeostasisdisorder is cholestasis. The beta-Klotho and FGF21 have been shown toinduce lipolysis in adipocytes and, therefore, reduced fat storage andincreased glucose uptake. Non-limiting examples of lipolysis/fat storagedisorders are obesity and associated metabolic and cardiovasculardiseases.

Based at least in part on the finding that FGF23 is able to stimulateexcretion of phosphate in the urine and thereby reduce phosphate levelsin the serum, Klotho-FGF23 fusion polypeptides of the disclosure can beused for treating or preventing hyperphosphatemia or calcinosis in anindividual. For example, it has been shown that a homozygous missensemutation in Klotho resulting in a deficiency in Klotho in a patient cancause severe tumoral calcinosis and artery calcification (Ichikawa etal., J. Clin. Invest. 117:2684-2691 (2007), which is herein incorporatedby reference). An individual is administered a pharmacologicallyeffective dose of a pharmaceutical composition containing the Klothofusion polypeptide, having at least one extracellular subdomain of aKlotho protein, a fibroblast growth factor and an (optional) modified Fcfragment so as to treat or prevent hyperphosphatemia or calcinosis. Inparticular, a Klotho fusion polypeptide containing at least oneextracellular domain of an alpha Klotho protein, a fibroblast growthfactor and an (optional) modified Fc fragment is useful for treatinghyperphosphatemia or calcinosis.

Klotho fusion polypeptides of the disclosure can also be used fortreating or preventing chronic renal disease or chronic renal failure inan individual. For example, it has been shown that Klotho expression isreduced in kidney of patients with chronic renal failure, compared tothat in unaffected kidneys (Koh et al., Biochem. Biophys. Res. Comm.280:1015-1020 (2001), which is herein incorporated by reference). Anindividual is administered a pharmacologically effective dose of apharmaceutical composition containing the Klotho fusion polypeptide,having at least one extracellular subdomain of a Klotho protein, afibroblast growth factor and an (optional) modified Fc fragment so as totreat or prevent chronic renal disease or chronic renal failure. Inparticular, a Klotho fusion polypeptide containing at least oneextracellular domain of an alpha Klotho protein is useful for treatingchronic renal disease or chronic renal failure.

Klotho fusion polypeptides of the disclosure can also be used fortreating or preventing cancer in an individual. For example, it has beenshown that Klotho expression is reduced in breast cancer tissue,compared to normal breast cancer tissue (Wolf et al., Oncogene (2008)advance online publication, which is herein incorporated by reference).An individual is administered a pharmacologically effective dose of apharmaceutical composition containing the Klotho fusion polypeptide,having at least one extracellular subdomain of a Klotho protein, afibroblast growth factor and an (optional) modified Fc fragment so as totreat or prevent cancer or breast cancer. In particular, a Klotho fusionprotein containing at least one extracellular domain of an alpha Klothoprotein is useful for treating cancer or breast cancer.

Methods for evaluating the efficacy and/or determining the effectivedose of a Klotho fusion polypeptide of the disclosure on an age-relateddisorder or metabolic disorder include organismal based assays, e.g.,using a mammal (e.g., a mouse, rat, primate, or some other non-human),or other animal (e.g., Xenopus, zebrafish, or an invertebrate such as afly or nematode). The Klotho fusion polypeptide can be administered tothe organism once or as a regimen (regular or irregular). A parameter ofthe organism is then evaluated, e.g., an age-associated parameter.Klotho fusion polypeptides that are of interest result in a change inthe parameter relative to a reference, e.g., a parameter of a controlorganism. Other parameters (e.g., related to toxicity, clearance, andpharmacokinetics) can also be evaluated.

The Klotho fusion polypeptide of the disclosure may be evaluated usingan animal that has a particular disorder, e.g., a disorder describedherein, e.g., an age-related disorder, a metabolic disorder. Thesedisorders can also provide a sensitized system in which the testpolypeptide's effects on physiology can be observed. Example disordersinclude: denervation, disuse atrophy; metabolic disorders (e.g.,disorder of obese and/or diabetic animals such as db/db mouse and ob/obmouse); cerebral, liver ischemia; cisplatin/taxol/vincristine models;various tissue (xenograph) transplants; transgenic bone models; painsyndromes (include inflammatory and neuropathic disorders); Paraquat,genotoxic, and oxidative stress models; and tumor I models.

For measuring an age-related disorder, the animal model can be an animalthat has an altered phenotype when calorically restricted. For example,F344 rats provide a useful assay system for evaluating a Klotho fusionpolypeptide. When calorically restricted, F344 rats have a 0 to 10%incidence of nephropathy. However, when fed ad libitum, they have a 60to 100% incidence of nephropathy.

To evaluate a Klotho fusion polypeptide of the disclosure, it isadministered to the animal (e.g., an F344 rat or other suitable animal)and a parameter of the animal is evaluated, e.g., after a period oftime. The animal can be fed ad libitum or normally (e.g., not undercaloric restriction, although some parameters can be evaluated undersuch conditions). Typically, a cohort of such animals is used for theassay. Generally, a test polypeptide can be indicated as favorablyaltering lifespan regulation in the animal if the test polypeptideaffects the parameter in the direction of the phenotype of a similaranimal subject to caloric restriction. Such test polypeptides may causeat least some of the lifespan regulatory effects of caloric restriction,e.g., a subset of such effects, without having to deprive the organismof caloric intake.

The parameter to be tested may be an age-associated or diseaseassociated parameter, e.g., a symptom of the disorder associated withthe animal model. For example, the test polypeptide can be administeredto a SH Rat, and blood pressure is monitored. A test polypeptide that isfavorably indicated can cause an amelioration of the symptom relative toa similar reference animal not treated with the polypeptide. Otherparameters relevant to a disorder or to aging can include: antioxidantlevels (e.g. antioxidant enzyme levels or activity), stress resistance(e.g., paraquat resistance), core body temperature, glucose levels,insulin levels, thyroid-stimulating hormone levels, prolactin levels,and leutinizing hormone levels.

To measure the effectiveness of the polypeptides of the disclosure fortreating an age-related disorder, an animal having decreased Klothoexpression may be used, e.g., mouse with a mutant Klotho; See Kuroo, etal. Nature, 390; 45 (1997) and U.S. Pub. No. 2003/0119910, both of whichare herein incorporated by reference in their entirety. For example, thetest polypeptide is administered to the mutant mouse and age-relatedparameters are monitored. A test polypeptide that is favorably indicatedcan cause an amelioration of the symptom relative to a similar referenceanimal not treated with the polypeptide. A parameter relevant to ametabolic disorder or to aging can be assessed by measurement of bodyweight, examination on the acquisition of reproductive ability,measurement of blood sugar level, observation of life span, observationof skin, observation of motor functions such as walking, and the like.The assessment can also be made by measurement of thymus weight,observation of the size of calcified nodules formed on the inner surfaceof thoracic cavity, and the like. Further, quantitative determination ofmRNA for the Klotho gene or Klotho protein is also useful for theassessment.

Still other in vivo models and organismal assays include evaluating ananimal for a metabolic parameter, e.g., a parameter relevant to aninsulin disorder, type II diabetes. Example metabolic parametersinclude: glucose concentration, insulin concentration, and insulinsensitivity.

Another example system features tumors, e.g., in an animal model. Thetumors can be spontaneous or induced. For example, the tumors can bedeveloped from cells that have a variety of genetic constitutions, e.g.,they can be p53+ or p53−. It is also possible to use organisms that anautoimmune disorder, e.g., an NZB mouse, which is predisposed to SLE. Toevaluate features of bone disease, it is possible, for example, to usean animal that has an ovariectomy as a model,. e.g., for osteoporosis.Similarly, for joint disease, the model can be based on adjuvantarthritis (e.g., mice can be immunized with cartilage proteoglycans,high mobility group proteins, streptococcal cell wall material, orcollagens); for kidney disease, kd/kd mice can be used. Animal models ofcognition, particularly learning and memory are also available. Animalmodels of diabetes and its complications are also available, e.g., thestreptozotocin model. Canine models can be used, for example, forevaluating stroke and ischemia.

In assessing whether a test polypeptide is capable of altering life spanregulation, a number of age-associated parameters or biomarkers can bemonitored or evaluated. Example age associated parameters include: (i)lifespan of the cell or the organism; (ii) presence or abundance of agene transcript or gene product in the cell or organism that has abiological age dependent expression pattern; (iii) resistance of thecell or organism to stress; (iv) one so or more metabolic parameters ofthe cell or organism (example parameters include circulating insulinlevels, blood glucose levels; fat content; core body temperature and soforth); (v) proliferative capacity of the cell or a set of cells presentin the organism; and (vi) physical appearance or behavior of the cell ororganism.

The term “average lifespan” refers to the average of the age of death ofa cohort of organisms. In some cases, the “average lifespan” is assessedusing a cohort of genetically identical organisms under controlledenvironmental conditions. Deaths due to mishap are discarded. Whereaverage lifespan cannot be determined (e.g., for humans) undercontrolled environmental conditions, reliable statistical information(e.g., from actuarial tables) for a sufficiently large population can beused as the average lifespan.

Characterization of molecular differences between two such organisms,e.g., one reference organism and one organism treated with a Klothofusion polypeptide can reveal a difference in the physiological state ofthe organisms. The reference organism and the treated organism aretypically the same chronological age. The term “chronological age” asused herein refers to time elapsed since a preselected event, such asconception, a defined embryological or fetal stage, or, more preferably,birth. A variety of criteria can be used to determine whether organismsare of the “same” chronological age for the comparative analysis.Typically, the degree of accuracy required is a function of the averagelifespan of a wildtype organism. For example, for the nematode C.elegans, for which the laboratory wildtype strain N2 lives an to averageof about 16 days under some controlled conditions, organisms of the sameage may have lived for the same number of days. For mice, organism ofthe same age may have lived for the same number of weeks or months; forprimates or humans, the same number of years (or within 2, 3, or 5years); and so forth. Generally, organisms of the same chronological agemay have lived for an amount of time within 15, 10, 5, 3, 2 or 1% of theaverage lifespan of a wildtype organism of that species. Preferably, theorganisms are adult organisms, e.g., the organisms have lived for atleast an amount of time in which the average wildtype organism hasmatured to an age at which it is competent to reproduce.

The organismal screening assay can be performed before the organismsexhibit overt physical features of aging. For example, the organisms maybe adults that have lived only 10, 30, 40, 50, 60, or 70% of the averagelifespan of a wildtype organism of the same species. Age-associatedchanges in metabolism, immune competence, and chromosomal structure havebeen reported. Any of these changes can be evaluated, either in a testsubject (e.g., for an organism based assay), or for a patient (e.g.,prior, during or after treatment with a therapeutic described herein.

A marker associated with caloric restriction can also be evaluated in asubject organism of a screening assay (or a treated subject). Althoughthese markers may not be age-associated, they may be indicative of aphysiological state that is altered when the Klotho pathway ismodulated. The marker can be an mRNA or protein whose abundance changesin calorically restricted animals. WO01/12851 and U.S. Pat. No.6,406,853 describe example markers. Cellular models derived from cellsof an animal described herein or analogous to an animal model describedherein can be used for a cell-based assay.

Models for evaluating the effect of a test polypeptide on muscle atrophyinclude: 1) rat medial gastrocnemius muscle mass loss resulting fromdenervation, e.g., by severing the right sciatic nerve at mid-thigh; 2)rat medial gastrocnemius muscle mass loss resulting from immobilization,e.g., by fixed the right ankle joint at 90 degrees of flexion; 3) ratmedial gastrocnemius muscle mass loss resulting from hind limbsuspension; (see, e.g., U.S. 2003-0129686); 4) skeletal muscle atrophyresulting from treatment with the cachectic cytokine, interleukin-1(IL-1) (R. N. Cooney, S. R. Kimball, T. C. Vary, Shock 7, 1-16 (1997));and 5) skeletal muscle atrophy resulting from treatment with theglucocorticoid, dexamethasone (A. L. Goldberg, J. Biol. Chem. 244,3223-9 (1969).)

Example animal models for AMD include: laser-induced mouse modelsimulating exudative (wet) macular degeneration Bora et al., Proc. Natl.Acad. Sci. USA., 100:2679-84 (2003); a transgenic mouse expressing amutated form of cathepsin D resulting in features associated with the“geographic atrophy” form of AMD (Rakoczy et al., Am. J. Pathol.,161:1515-24 (2002)); and a transgenic mouse over expressing VEGF in theretinal pigment epithelium resulting in CNV. Schwesinger et al., Am. J.Pathol. 158:1161-72 (2001).

Example animal models of Parkinson's disease include primates renderedParkinsonian by treatment with the dopaminergic neurotoxin 1-methyl-4phenyl 1,2,3,6-tetrahydropyridine (MPTP) (see, e.g., U.S. PatentPublication No. 20030055231 and Wichmann et al., Ann. N.Y. Acad. Sci.,991:199-213 (2003); 6-hydroxydopamine-lesioned rats (e.g., Lab. Anim.Sci.,49:363-71 (1999)) ; and transgenic invertebrate models (e.g., Laksoet al., J. Neurochem. 86:165-72 (2003) and Link, Mech. Ageing Dev.,122:1639-49 (2001)).

Example molecular models of Type II diabetes include: a transgenic mousehaving defective Nkx-2.2 or Nkx-6.1; (U.S. Pat. No. 6,127,598); ZuckerDiabetic Fatty fa/fa (ZDF) rat. (U.S. Pat. No. 6,569,832); and Rhesusmonkeys, which spontaneously develop obesity and subsequently frequentlyprogress to overt type 2 diabetes (Hotta et al., Diabetes, 50:1126-33(2001); and a transgenic mouse with a dominant-negative IGF-I receptor(KR-IGF-IR) having Type 2 diabetes-like insulin resistance.

Example animal and cellular models for neuropathy include: vincristineinduced sensory-motor neuropathy in mice (U.S. Pat. No. 5,420,112) orrabbits (Ogawa et al., Neurotoxicology, 21:501-11 (2000)); astreptozotocin (STZ)-diabetic rat for study of autonomic neuropathy(Schmidt et al., Am. J Pathol., 163:21-8 (2003)); and a progressivemotor neuropathy (pmn) mouse (Martin et al., Genomics, 75:9-16 (2001)).

Example animal models of hyperphosphatemia or tumoral calcinosis includeKlotho knockout mice and FGF23 knockout mice (Yoshida et al.,Endocrinology 143:683-689 (2002)).

Example animal models of chronic renal disease or chronic renal failureinclude COL4A3+/−mice (Beirowski et al., J. Am. Soc. Nephrol.17:1986-1994 (2006)).

Example animal models of cancer include the transplantation orimplantation of cancer cells or tissue into nude mice, as is known inthe art (Giovanella et al., Adv. Cancer Res. 44:69-120 (1985)). Forexample, animal models of breast cancer include nude mice transplantedor implanted with breast cancer cells or tissue (e.g., Yue et al.,Cancer Res. 54:5092-5095 (1994); Glinsky et al., Cancer Res.56:5319-5324 (1996); Visonneau Am. J. Path. 152:1299-1311 (1998)).

The compositions can be administered to a subject, e.g., an adultsubject, particularly a healthy adult subject or a subject having anage-related disease. In the latter case, the method can includeevaluating a subject, e.g., to characterize a symptom of an age-relateddisease or other disease marker, and thereby identifying a subject ashaving a neurodegenerative disease, e.g., Alzheimer's or an age-relateddisease or being predisposed to such a disease.

Skeletal Muscle Atrophy

Methods or uses of the disclosure which provide administering the Klothofusion polypeptide to an individual can be used to treat skeletal muscleatrophy. Muscle atrophy includes numerous neuromuscular, metabolic,immunological and neurological disorders and diseases as well asstarvation, nutritional deficiency, metabolic stress, diabetes, aging,muscular dystrophy, or myopathy. Muscle atrophy occurs during the agingprocess. Muscle atrophy also results from reduced use or disuse of themuscle. Symptoms include a decline in skeletal muscle tissue mass. Inhuman males, muscle mass declines by one-third between the ages of 50and 80. Some molecular features of muscle atrophy include theupregulation of ubiquitin ligases, and the loss of myofibrillar proteins(Furuno et al., J. Biol. Chem., 265:8550-8557, 1990). The breakdown ofthese proteins can be followed, e.g., by measuring 3-methyl-histidineproduction, which is a specific constituent of actin, and in certainmuscles of myosin (Goodman, Biochem. J. 241:121-12, 1987 and Lowell, etal., Metabolism, 35:1121-112, 1986; Stein and Schluter, Am. J. Physiol.Endocrinol. Metab. 272: E688-E696, 1997). Release of creatine kinase (acell damage marker) (Jackson, et al., Neurology, 41: 101 104, 1991) canalso be indicative.

Non-Insulin-Dependent Diabetes

Methods or uses of the disclosure which provide administering the Klothofusion polypeptide to an individual can be used to treatNon-insulin-dependent Diabetes. Non-insulin-dependent Diabetes is alsocalled “adult onset” diabetes and Type 2 diabetes. Type 2 diabetes alsoincludes “non-obese type 2” and “obese type 2.” Type II diabetes can becharacterized by (1) reduced pancreatic-beta-islet-cell secretion ofinsulin such that less than necessary amounts of insulin are produced tokeep blood glucose levels in balance and/or (2) “insulin resistance,”wherein the body fails to respond normally to insulin. (U.S. Pat. No.5,266,561 and U.S. Pat. No. 6,518,069). For example, glucose-stimulatedinsulin levels typically fail to rise above 4.0 nmol/L. (U.S. Pat. No.5,266,561). Example symptoms of Type II diabetes include: hyperglycemiawhile fasting (U.S. Pat. No. 5,266,561); fatigue; excessive thirst;frequent urination; blurred vision; and an increased rate of infections.Molecular indications of Type II diabetes include islet amyloiddeposition in the pancreases.

Neuropathy

Neuropathy can include a central and/or peripheral nerve dysfunctioncaused by systemic disease, hereditary condition or toxic agentaffecting motor, sensory, sensorimotor or autonomic nerves. (see, e.g.,US Patent Application No. 20030013771). Symptoms can vary depending uponthe cause of the nerve damage and the particular types of nervesaffected. For example, symptoms of motor neuropathy include clumsinessin performing physical tasks or as muscular weakness, exhaustion afterminor exertion, difficulty in standing or walking and attenuation orabsence of a neuromuscular reflex. (U.S. Patent Application No.20030013771) symptoms of autonomic neuropathy include constipation,cardiac irregularities and attenuation of the postural hypotensivereflex. (U.S. Patent Application No. 20030013771), symptoms of sensoryneuropathy include pain and numbness; tingling in the hands, legs orfeet; and extreme sensitivity to touch, and symptoms of retinopathyinclude blurred vision, sudden loss of vision, black spots, and flashinglights.

Alzheimer's Disease

Methods or uses of the disclosure which provide administering the Klothofusion polypeptide to an individual can be used to treat Alzheimer'sDisease (AD). Alzheimer's Disease is a complex neurodegenerative diseasethat results in the irreversible loss of neurons. It provides merely oneexample of a neurodegenerative disease that is also an age-relatedcondition. Clinical hallmarks of Alzheimer's Disease include progressiveimpairment in memory, judgment, orientation to physical surroundings,and language. Neuropathological hallmarks of AD include region-specificneuronal loss, amyloid plaques, and neurofibrillary tangles. Amyloidplaques are extracellular plaques containing the amyloid peptide (alsoknown as Ap, or Ap42), which is a cleavage product of the, 8-amyloidprecursor protein (also known as APP). Neurofibrillary tangles areinsoluble intracellular aggregates composed of filaments of theabnormally hyperphosphorylated microtubule-associated protein, tautAmyloid plaques and neurofibrillary tangles may contribute to secondaryevents that lead to neuronal loss by apoptosis (Clark and Karlawish,Ann. Intern. Med. 138(5):400-410 (2003). For example, p-amyloid inducescaspase-2-dependent apoptosis in cultured neurons (Troy et al. JNeurosci. 20(4):1386-1392). The deposition of plaques in viva maytrigger apoptosis of proximal neurons in a similar manner.

A variety of criteria, including genetic, biochemical, physiological,and cognitive criteria, can be used to evaluate AD in a subject.Symptoms and diagnosis of AD are known to medical practitioners. Someexample symptoms and markers of AD are presented below. Informationabout these indications and other indications known to be associatedwith AD can be used as an “AD-related parameter.” An AD relatedparameter can include qualitative or quantitative information. Anexample of quantitative information is a numerical value of one or moredimensions, e.g., a concentration of a protein or a tomographic map.Qualitative information can include an assessment, e.g., a physician'scomments or a binary (“yes”/“no”) and so forth. An AD-related parameterincludes information that indicates that the subject is not diagnosedwith AD or does not have a particular indication of AD, e.g., acognitive test result that is not typical of AD or a genetic APOEpolymorphism not associated with AD.

Progressive cognitive impairment is a hallmark of AD. This impairmentcan present as decline in memory, judgment, decision making, orientationto physical surroundings, and language (Nussbaum and Ellis, New Eng J.Med. 348(14):1356 35 1364 (2003)). Exclusion of other forms of dementiacan assist in making a diagnosis of AD. Neuronal death leads toprogressive cerebral atrophy in AD patients. Imaging techniques (e.g.,magnetic resonance imaging, or computer assisted tomography) can be usedto detect AD-associated lesions in the brain and/or brain atrophy.

AD patients may exhibit biochemical abnormalities that result from thepathology of the disease. For example, levels of tan protein in thecerebrospinal fluid is elevated in AD patients (Andreasen, N. et al.Arch Neurol. 58:349-350 (2001)).

Levels of amyloid beta 42 (A,B42) peptide can be reduced in CSF of ADpatients. Levels of Ap42 can be increased in the plasma of AD patients(Ertekein-Taner, N., et al. Science 290:2303 2304 (2000)). Techniques todetect biochemical abnormalities in a sample from a subject includecellular, immunological, and other biological methods known in the art.For general guidance, see, e.g., techniques described in Sambrook &Russell, Molecular Cloning: A Laboratory Manual, 3rd Edition, ColdSpring Harbor Laboratory, N.Y. (2001), Ausubel et al., Current Protocolsin Molecular Biology (Greene Publishing Associates and WileyInterscience, N.Y. (1989), (Harrow, E. and Lane, D. (1988) Antibodies: ALaboratory Manual, Cold Spring Harbor Laboratory Press, Cold SpringHarbor, N.Y.), and updated editions thereof.

For example, antibodies, other immunoglobulins, and other specificbinding ligands can be used to detect a biomolecule, e.g., a protein orother antigen associated with AD. For example, one or more specificantibodies can be used to probe a sample. Various formats are possible,e.g., ELISAs, fluorescence-based assays, Western blots, and proteinarrays. Methods of producing polypeptide arrays are described in theart, e.g., in De Wildt et al. (2000). Nature Biotech. 18, 989-994;Lucking et al. (1999). Anal. Biochem. 270, 103-111; Ge, H. (2000).Nucleic Acids Res. 28, e3, I-VII; MacBeath, G., and Schreiber, S. L.(2000). Science 289, 1760 to 1 763; and WO 99/5 1 773A1.

In one assay, a non-human animal model of AD (e.g., a mouse model) isused, e.g., to evaluate a polypeptide or a therapeutic regimen. Forexample, U.S. Pat. No. 6,509,515 describes one such model animal whichis naturally able to be used with learning and memory tests. The animalexpresses an amyloid precursor protein (APP) sequence at a level inbrain tissues such that the animal develops a progressive necrologicdisorder within a short period of time from birth, generally within ayear from birth, preferably within 2 to 6 months, from birth. The APPprotein sequence is introduced into the animal, or an ancestor of theanimal, at an embryonic stage, preferably the one cell, or fertilizedoocyte, stage, and generally not later than about the 8-cell stage. Thezygote or embryo is then developed to term in a pseudo-pregnant asfoster female. The amyloid precursor protein genes are introduced intoan animal embryo so as to be chromosomally incorporated in a state whichresults in super endogenous expression of the amyloid precursor proteinand the development of a progressive necrologic disease in thecortico-limbic areas of the brain, areas of the brain which areprominently affected in progressive necrologic disease states such asAD. The gliosis and clinical manifestations in affected transgenicanimals model necrologic disease. The progressive aspects of theneurologic disease are characterized by diminished exploratory and/orlocomotor behavior and diminished deoxyglucose uptake/utilization andhypertrophic gliosis in the cortico-limbic regions of the brain.Further, the changes that are seen are similar to those that are seen insome aging animals. Other animal models are also described in U.S. Pat.Nos. 5,387,742; 5,877,399; 6,358,752; and 6,187,992.

Parkinson's Disease

Methods or uses of the disclosure which provide administering the Klothofusion polypeptide to an individual can be used to treat Parkinson'sDisease. Parkinson's disease includes neurodegeneration of dopaminergicneurons in the substantia nigra resulting in the degeneration of thenigrostriatal dopamine system that regulates motor function. Thispathology, in turn, leads to motor dysfunctions. (see, e.g., andLotharius et al., Nat. Rev. Neurosci., 3:932-42 (2002)). Example motorsymptoms include: akinesia, stooped posture, gait difficulty, posturalinstability, catalepsy, muscle rigidity, and tremor. Example non-motorsymptoms include: depression, lack of motivation, passivity, dementiaand gastrointestinal dysfunction (see, e. g., Fahn, Ann. N.Y. Acad.Sci., 991:1-14 (2003) and Pfeiffer, Lancet Neurol., 2:107-16 (2003))Parkinson's has been observed in 0.5 to 1 percent of persons 65 to 69years of age and 1 to 3 percent among persons 80 years of age and older.(see, e.g., Nussbaum et al., N. Engl. J. Med., 348:1356-64 (2003)).Molecular markers of Parkinson's disease include reduction in aromatic Lamino acid decarboxylase (AADC) (see, e.g., US App. No. 20020172664);and loss of dopamine content in the nigrostriatal neurons (see, e.g.,Fahn, Ann. N.Y. Acad. Sci., 991:1-14 (2003) and Lotharius et al., Nat.Rev. Neurosci., 3:932-42 (2002)). In some familial cases, PD is linkedto mutations in single genes encoding alpha-synuclein and parkin (an E3ubiquitin ligase) proteins. (e.g., Riess et al., J. Neurol. 250 Suppl1:13 10 (2003) and Nussbaum et al., N. Engl. J. Med., 348:1356-64(2003)). A missense mutation in a neuron-specific C-terminal ubiquitinhydrolase gene is also associated with Parkinson's. (e.g., Nussbaum etal., N. Engl. J. Med., 348:1356-64 (2003))

Huntington's Disease

Methods or uses of the disclosure which provide administering the Klothofusion polypeptide to an individual can be used to treat Huntington'sDisease. Methods for evaluating the efficacy and/or determining theeffective dose of a Klotho fusion polypeptide on Huntington's Diseaseinclude organismal based assays, e.g., using a mammal (e.g., a mouse,rat, primate, or some other non-human), or other animal (e.g., Xenopus,zebrafish, or an invertebrate such as a fly or nematode). A number ofanimal model system for Huntington's disease are available. See, e.g.,Brouillet, Functional Neurology 15(4): 239-251 (2000); Ona et al. Nature399: 263-267 (1999), Bates et al. Hum Mol Genet. 6(10):1633-7 (1997);Hansson et al. J. of Neurochemistry 78: 694-703; and Rubinsztein, D. C.,Trends in Genetics, Vol. 1S, No. 4, pp. 202-209 (a review on variousanimal and non-human models of HD).

An example of such an animal model is the transgenic mouse strain is theR6/2 line (Mangiarini et al. Cell 87: 493-506 (1996)). The R6/2 mice aretransgenic Huntington's disease mice, which over-express exon 1 of thehuman HD gene (under the control of the endogenous promoter). The exon 1of the R6/2 human HD gene has an expanded CAG/polyglutamine repeatlengths (150 CAG repeats on average). These mice develop a progressive,ultimately fatal neurological disease with many features of humanHuntington's disease. Abnormal aggregates, constituted in part by the Nterminal part of Huntingtin (encoded by HD exon 1), are observed in R6/2mice, both 45 in the cytoplasm and nuclei of cells (Davies et al. Cell90: 537-548 (1997)). For example, the human Huntingtin protein in thetransgenic animal is encoded by a gene that includes at least 55 CAGrepeats and more preferably about 150 CAG repeats. These transgenicanimals can develop a Huntington's disease-like phenotype.

These transgenic mice are characterized by reduced weight gain, reducedlifespan and motor impairment characterized by abnormal gait, restingtremor, hindlimb clasping and hyperactivity from 8 to 10 weeks afterbirth (for example the R6/2 strain; see Mangiarini et al. Cell 87:493-506 (1996)). The phenotype worsens progressively toward hypokinesia.The brains of these transgenic mice also demonstrate neurochemical andhistological abnormalities, such as changes in neurotransmitterreceptors (glutamate, dopaminergic), decreased concentration ofN-acetylaspartate (a marker of neuronal integrity) and reduced striatumand brain size. Accordingly, evaluating can include assessing parametersrelated to neurotransmitter levels, neurotransmitter receptor levels,brain size and striatum size. In addition, abnormal aggregatescontaining the transgenic part of or full-length human Huntingtinprotein are present in the brain tissue of these animals (e.g., the R6/2transgenic mouse strain). See, e.g., Mangiarini et al. Cell 87: 493-506(1996), Davies et al. Cell 90: 537-548 (1997), Brouillet, FunctionalNeurology 15(4): 239-251 (2000) and Cha et al. Proc. Natl. Acad. Sci.USA 95: 6480-6485 (1998).

To test the effect of the test polypeptide or known polypeptidedescribed in the application in an animal model, differentconcentrations of test polypeptide are administered to the transgenicanimal, for example by injecting the test polypeptide into circulationof the animal. A Huntington's disease-like symptom may be evaluated inthe animal. The progression of the Huntington's disease-like symptoms,e.g., as described above for the mouse model, is then monitored todetermine whether treatment with the test polypeptide results inreduction or delay of symptoms. In another assay, disaggregation of theHuntingtin protein aggregates in these animals is monitored. The animalcan then be sacrificed and brain slices are obtained. The brain slicesare then analyzed for the presence of aggregates containing thetransgenic human Huntingtin protein, a portion thereof, or a fusionprotein comprising human Huntingtin protein, or a portion thereof. Thisanalysis can includes, for example, staining the slices of brain tissuewith anti-Huntingtin antibody and adding a secondary antibody conjugatedwith FITC which recognizes the anti-Huntington's antibody (e.g., theanti-Huntingtin antibody is mouse anti-human antibody and the secondaryantibody is specific for human antibody) and visualizing the proteinaggregates by fluorescent microscopy.

A variety of methods are available to evaluate and/or monitorHuntington's disease. A variety of clinical symptoms and indicia for thedisease are known. Huntington's disease causes a movement disorder,psychiatric difficulties and cognitive changes. The degree, age ofonset, and manifestation of these symptoms can vary. The movementdisorder can include quick, random, dance-like movements called chorea.

Example motor evaluations include: ocular pursuit, saccade initiation,saccade velocity, dysarthria, tongue protrusion, finger tap ability,pronate/supinate, a lo fist-hand-palm sequence, rigidity of arms,bradykinesia, maximal dystonia (trunk, upper and lower extremities),maximal chorea (e.g., trunk, face, upper and lower extremities), gait,tandem walking, and retropulsion. An example treatment can cause achange in the Total Motor Score 4 (TMS-4), a subscale of the UHDRS,e.g., over a one-year period.

Cancer

Methods or uses of the disclosure which provide administering the Klothofusion polypeptide to an individual can be used to treat cancer. Cancerincludes any disease that is caused by or results in inappropriatelyhigh levels of cell division, inappropriately low levels of apoptosis,or both. Examples of cancers include, without limitation, leukemias(e.g., acute leukemia, acute lymphocytic leukemia, acute myelocyticleukemia, acute myeloblastic leukemia, acute promyelocytic leukemia,acute myelomonocytic leukemia, acute monocytic leukemia, acuteerythroleukemia, chronic leukemia, chronic myelocytic leukemia, chroniclymphocytic leukemia), polycythemia vera, lymphoma (Hodgkin's disease,non-Hodgkin's disease), Waldenstrom's macroglobulinemia, heavy chaindisease, and solid tumors such as sarcomas and carcinomas (e.g.,fibrosarcoma, myxosarcoma, liposarcoma, chondrosarcoma, osteogenicsarcoma, chordoma, angiosarcoma, endotheliosarcoma, lymphangiosarcoma,lymphangioendotheliosarcoma, synovioma, mesothelioma, Ewing's tumor,leiomyosarcoma, rhabdomyosarcoma, colon carcinoma, pancreatic cancer,breast cancer, ovarian cancer, prostate cancer, squamous cell carcinoma,basal cell carcinoma, adenocarcinoma, sweat gland carcinoma, sebaceousgland carcinoma, papillary carcinoma, papillary adenocarcinomas,cystadenocarcinoma, medullary carcinoma, bronchogenic carcinoma, renalcell carcinoma, hepatoma, nile duct carcinoma, choriocarcinoma,seminoma, embryonal carcinoma, Wilm's tumor, cervical cancer, uterinecancer, testicular cancer, lung carcinoma, small cell lung carcinoma,bladder carcinoma, epithelial carcinoma, glioma, astrocytoma,medulloblastoma, craniopharyngioma, ependymoma, pinealoma,hemangioblastoma, acoustic neuroma, oligodenroglioma, schwannoma,meningioma, melanoma, neuroblastoma, and retinoblastoma).Lymphoproliferative disorders are also considered to be proliferativediseases.

All patents, patent applications, and published references cited hereinare hereby incorporated by reference in their entirety. While thisdisclosure has been particularly shown and described with references toembodiments thereof, it will be understood by those skilled in the artthat various changes in form and details may be made therein withoutdeparting from the scope of the disclosure encompassed by the appendedclaims.

5. EXAMPLES Example 1 Expression and Purification of Klotho FusionPolypeptides

Expression of the Klotho Fusion Polypeptide

The polypeptides of the disclosure were made by transiently transfectingHEK293T cells with an expression vector encoding a Klotho fusionpolypeptide having the extracellular domain of alpha Klotho and theFGF23 (R179Q) variant. Conditioned media containing expressedpolypeptides were generated by transient transfection of the respectiveexpression plasmids for Klotho, FGF23, and the Klotho-FGF23(R179Q)fusion protein. The transfections were performed in 6-well plates usingLipofectamine 2000 (Invitrogen, Cat #11668-019). Five hours aftertransfection, the transfection mix was replaced with 3 ml DMEM plus 1%FBS. Conditioned media were collected 72 hours after the addition of 3ml DMEM plus 1% FBS. Samples of conditioned medium from varioustransiently transfected HEK293T cells were separated bySDS-polyacrylamide gel electrophoresis (SDS-PAGE) and analyzed byWestern blot (FIG. 3A) or stained with Coomassie blue (FIG. 3B).

SDS-polyacrylamide gel electrophoresis was performed on various samples(lane 1, Control; lane 2, FGF23; lane 3, sKlotho; lanes 4-6,sKlotho-FGF23). Coomassie blue staining revealed the expression of ahigh, >180 kDa band (FIG. 3B, indicated by arrow on the right) that wasnot present in lanes 1-3, which contained samples that had not beentransfected with the vector encoding the Klotho fusion polypeptide. Thequality of the Klotho fusion polypeptide secreted into the media wasevaluated by Western blot (FIG. 3A). An anti-FGF23 rat monoclonal IgG2A(R&D Systems, Cat #MAB26291) was used as the primary antibody to detectthe Klotho fusion polypeptides by Western blot. The Western blotconfirmed that the additional bands observed in the Coomassie stainedgels were Klotho fusion polypeptides. The Western blot confirmed thatthe Klotho fusion polypeptides had the expected molecular weight for theKlotho fusion polypeptide. This analysis shows the expression of theKlotho-FGF23(R179Q) fusion protein.

Purification of the Klotho Fusion Polypeptide

The polypeptides of the disclosure were purified from conditioned mediafrom a culture of HEK293T cells transiently transfected with anexpression vector encoding a Klotho fusion polypeptide having theextracellular domain of alpha Klotho and the FGF23 R179Q variant. Togenerate conditioned medium, an expression vector encodingsKlotho-FGF23-6×His was transfected (500 μg DNA in 18 ml of OptiMEM 1(GIBCO, Cat #11058) mixed with 18 ml of 2 μg/ml polyethlinimine (PEI)into HEK293 cells grown in suspension in expression medium (464 ml ofHEK293T cells at 10⁶ cells/ml in Freestype 293 expression medium (GIBCO,Cat #12338)). After transfection, the culture was allowed to grow (120hours; 37° C. in a 5% CO₂ incubator; shaking at 125 rpm). At the end ofincubation, conditioned medium was harvested by centrifugation (1000 rpmfor five minutes). The conditioned medium was then applied to anickel-agarose column. The sKlotho-FGF23-6×His bound tightly to thecolumn and was eluted with 50 mM imidazole. The resulting purifiedmaterial was then dialyzed in PBS to remove imidazole. A sample of thepurified sKlotho-FGF23-6×His was separated by SDS-PAGE (lane 1, purifiedsKlotho-FGF23-6×His; lane 2, molecular weight marker) and analyzed bystaining with Coomassie blue (FIG. 3C). The stained SDS-PAGE gelconfirmed that the purified sKlotho-FGF23-6×His had the expectedmolecular weight. The inability to detect bands corresponding toproteins other than full-length sKlotho-FGF23-6×His in the lane loadedwith the purified material also showed that the sKlotho-FGF23-6×His waspurified.

Example 2 In Vitro Assay Assessing the Activity of the Klotho FusionPolypeptide

Egr-1-luciferase

The biological activity of the expressed alpha Klotho fusion polypeptidewas tested in Egr-1-luciferase reporter assays. Binding of the Klothofusion polypeptide to the FGF23 receptor resulted in the downstreamactivation of Egr-1 and the expression of a luciferase reporterregulated by the Egr-1 promoter. The Egr-1-luciferase reporter gene wasconstructed based on that reported by Urakawa et al. (Nature, 2006, Vol444, 770-774). HEK293T cells seeded in 48-well poly-D-lysine plate weretransfected with the Egr-1-luciferase reporter gene together with atransfection normalization reporter gene (Renilla luciferase). Fivehours after transfection of the Egr-1 luciferase reporter gene, thetransfection mix was replaced with 3 ml DMEM plus 1% FBS. Conditionedmedia were collected 72 hours after the addition of 3 ml DMEM plus 1%FBS. Five hours later, the transfection mix was replaced with a sampleto be tested for activity. In initial experiments, 50% conditionedmedium (alone or containing Klotho, FGF23, Klotho and FGF23, and theKlotho-FGF23(R179Q) fusion protein) and 50% DMEM with 1% FBS in thepresence or absence of 20 μg/ml heparin (Sigma, Cat #H8537; dissolved inDMEM as 2 mg/ml stock) were tested in the Egr-1-luciferase reporterassays (FIG. 4). Further experiments used defined quantities of thepurified polypeptides (FIGS. 5A and 5B). Cells were lysed 20 hours laterin passive lysis buffer (Promega, Cat #E194A) and luciferase activitieswere determined using Dual-Glo Luciferase Assay System (Promega, Cat#E2940).

In initial experiments, Klotho fusion polypeptide activity wasdemonstrated in unfractionated conditioned medium. Using theEgr-1-luciferase reporter gene (FIG. 4) these experiments quantified thefold changes in the expression of the luciferase reporter. Conditionedmedium containing a combination of FGF23 and the extracellular domain ofKlotho protein activated Egr-1-luciferase, but conditioned mediumcontaining only FGF23 or conditioned medium containing only theextracellular domain of Klotho, did not activate Egr-1-luciferase.Conditioned medium containing the fusion protein sKlotho-FGF23(R179Q)activated the Egr-1-luciferase reporter gene in contrast to conditionedmedia containing either FGF23 or Klotho alone. In these experiments,conditioned medium containing the fusion protein sKlotho-FGF23(R179Q)activated the Egr-1-luciferase reporter gene significantly better thanconditioned medium containing a combination of FGF23 and Klotho. In thepresence of heparin, the inductions by conditioned medium containing thefusion protein sKlotho-FGF23(R179Q) and the conditioned mediumcontaining a combination of FGF23 and Klotho were significantlyenhanced. Table 1 lists the relative expression of various FGF-Klothofusion polypeptides in conditioned medium and the relative activity ofthe unfractionated conditioned medium corresponding to the variousFGF-Klotho fusion polypeptides in Egr-1-luciferase reporter assays.

TABLE 1 Expression and Activities of sKlotho-FGF23 fusion variantsActivity in Egr-1-luc sKlotho-FGF23 fusion constructs Expressionreporter gene 1 sKlotho-FGF23 good yes 2 IgG sp-sKlotho-FGF23 good yes 3sKL-D1-FGF23 good no 4 sKL-D2-FGF23 no n.a. 5 s(KL-D1)2-FGF23 good no 6sKL-D1/D2-FGF23 no n.a. 7 ssKlotho(ΔN-26)-FGF23 poor no* 8sKLD1-D2(Δ692-965)-FGF23 poor no* 9 sKL-D1-D2(Δ507-798)-FGF23 poor no*10 FGF23-sKlotho poor no* *lack of activity may be the result of lowexpression

Egr-1-luciferase reporter assays were also performed using definedquantities of proteins purified from the conditioned medium, using thepurification procedure as described in Example 1. Consistent withprevious results using unfractionated conditioned medium containing theexpressed polypeptides, treatment with a combination of purified FGF23and sKlotho resulted in luciferase reporter activity, but treatment withpurified FGF23 alone did not (FIG. 5A). The luciferase reporter activityfrom the combination of purified FGF23 and sKlotho was further dependenton the dose of purified sKlotho, and the effect could be enhanced by thepresence of heparin (20 μg/ml). An effect of the sKlotho-FGF23-6×Hisfusion polypeptide on luciferase activity could be detected atconcentrations as low as about 1.21 nM (1.2 fold change) and at least upto about 19.3 nM (2.4 fold change) in Egr-1-luciferase reporter assays(FIG. 5B). The activity of the sKlotho-FGF23-6×His fusion polypeptide onluciferase activity was significantly enhanced in the presence ofheparin (20 μg/ml). In the presence of heparin, the effect of thesKlotho-FGF23-6×His fusion polypeptide on luciferase activity could bedetected at a concentration as low as about 0.6 nM (2.0 fold change).The result showed that purified sKlotho-FGF23-6×His dose-dependentlyinduced the EGR-1-luc reporter gene, and that treatment withsKlotho-FGF23-6×His.

Example 3 In Vitro Assay Assessing the Effect of the Klotho fusionPolypeptide on Muscle Cells

The biological effect of the expressed Klotho fusion polypeptide wastested on C2C12 myoblasts. Treatment of C2C12 myoblasts with IGF-1,FGF2, or sKlotho-FGF23 resulted in myotube growth and phosphorylation ofsignaling proteins. C2C12 myoblasts were seeded at a density of 40,000cells/well in 6-well poly-D-lysine and fibronectin coated plates ingrowth medium (3 parts DMEM and 1 part F12), 10% FBS, 1% Glut; 1% P/S;1% Linolic acid; 0.1% ITS: [insulin (10 mg/ml), transferrin (5.5 mg/ml),and selenium (5 ng/ml)]. After myoblasts reached confluence (3 days),medium was changed into differentiation medium (DMED with 2% horseserum; 1% Glut; 1% P/S).

For the myotube diameter experiments, three days after confluent mediawas changed into differentiation medium, cells were treated with IGF-1(10 nM), FGF2 (20 ng/ml) or sKlotho-FGF23 (20 nM) in the absence orpresence of dexamethasone (100 μM) for 24 hours in differentiationmedium. At the end of treatment, cells were fixed with glutaraldehyde(5% in PBS) and multiple fluorescent images were collected. Myotubediameter was measured using the Pipeline Pilot program to determinehypertrophy or atrophy.

For the signaling protein phosphorylation,experiments, three days afterconfluent media was changed into differentiation medium, cells werestarved for four hours with DMEM without FBS and then treated with IGF-1(10 nM), FGF2 (20 ng/ml) or sKlotho-FGF23 (20 nM) in the absence orpresence of Rapamycin (40 nM) for 30 min. Cells were lysed in RIPAbuffer in the presence of protease and phosphatase inhibitors. Westernblot analysis was carried out and membranes were probed with differentantibodies as indicated in the figure and developed on X-ray films,which were scanned.

The results of this study showed that sKlotho-FGF23 resulted in anincrease in myotube diameter compared to the control and induced C2C12myotube hypertrophy similar to results for IGF-1 and FGF2 (FIG. 5A). Inaddition, treatment with sKlotho-FGF23, IGF-1, and FGF2 could partiallyreverse myotube atrophy induced by dexamethasone, based on measurementsof myotube diameter. No difference was observed between sKlotho-FGF23and FGF2 on myotube morphology (measured by thickness of the myotubes)in the absence or presence of dexamethasone. The trophic effects ofsKlotho-FGF23, IGF-1, and FGF2 were statistically significant.

Consistent with the effects on C2C12 myotubes, sKlotho-FGF23 fusionprotein signaling led to the phosphorylation of p70S6K and ERK, but notAKT or FoxO, in C2C12 myotubes (FIG. 5B). The effect of sKlotho-FGF23 onsignaling was similar to that of FGF2, but was distinct from that ofIGF-1. The extent of ERK phosphorylation by sKlotho-FGF23 was observedto be less than that of IGF-1 or FGF2. The phosphorylation of p70S6K bysKlotho-FGF23 was rapamycin sensitive. In the experiments involvingC2C12 cells, heparin was not required to activate signaling. Theseresults show that a sKlotho-FGF23 fusion polypeptide activated signalingin C2C12 myotubes.

Example 4 Fusion Polypeptides Comprising sKlotho, FGF23 and FcLALA

Various fusion polypeptides are constructed using sKlotho, FGF23, and amodified Fc fragment of an antibody. These modified Fc molecules havealtered (decreased) binding to FcRn and thus increased serum half-life.They also have modified bioavailability and alterered transport tomucosal surfaces and other targets in the body. In this example, theFGF23 and sKlotho are fused to FcLALA, which is described in U.S. Pat.No. 7,217,798 and Hessell et al. 2007 Nature 449:101-104, Interveningbetween the various components of these fusion polypeptides are linkers,as described in Lode et al. 1998 Proc. Natl. Acad. Sci. USA 95:2475-2480. These fusions are inserted into constructs, e.g., pcDNA3.1(Invitrogen, Carlsbad, Calif.), and expressed in HEK293 cells.

A. sKlotho-FGF23-FcLALA v1

A fusion is constructed which comprises: sKlotho, a linker, FGF23,another linker, and FcLALA. This embodiment, designatedsKlotho-FGF23-FcLALA v1, is presented in SEQ ID NOs: 46 and 47, below.

The nucleotide sequence of sKlotho-FGF23-FcLALA v1 (wherein initiationATG as 1) is presented as SEQ ID NO: 46.

The amino acid sequence of sKlotho-FGF23-FcLALA v1 is presented below asSEQ ID NO: 47.

In this sequence, the various components of the fusion are as follows:

sKlotho: 1-982; Linked: 983-1001; FGF23: 1002-1228; Linker 2; 1229-1233;FcLALA: 1234-1459.

B. sKlotho-FGF23-FcLALA v2

A fusion is constructed which comprises: sKlotho, a linker, FGF23,another linker, and FcLALA. This embodiment is designatedsKlotho-FGF23-FcLALA v2 and presented as SEQ ID NOs: 48 and 49, below.

The nucleotide sequence of sKlotho-FGF23-FcLALA v2 (wherein initiationATG as 1) is presented as SEQ ID NO: 48.

The amino acid sequence of sKlotho-FGF23-FcLALA v2 is presented below asSEQ ID NO: 49.

In this sequence, the various components of the fusion are as follows:

sKlotho: (aa or amino acids) 1-982; Linker 1: 983-1001; FGF23:1002-1228; Linker 2; 1229-1233; FcLALA: 1234-1450.

Other fusion polypeptides can be constructed by combining in variouscombinations the FGF, Klotho, modified Fc fragments, and (optionally)linker sequences, and variants and derivatives thereof, as describedherein or known in the art.

Example 5 Fusion Polypeptides Comprising FGF23 and FcLALA

Various fusion polypeptides are constructed using FGF23, and a modifiedFc fragment of an antibody, as described in U.S. Pat. No. 7,217,798.These modified Fc molecules have altered (decreased) binding to FcRn andthus increased serum half-life. They also have modified bioavailabilityand alterered transport to mucosal surfaces and other targets in thebody. In this example, FGF23 is fused to FcLALA, Intervening between thevarious components of these fusion polypeptides are linkers, asdescribed in Lode et al. 1998 Proc. Natl. Acad. Sci. USA 95: 2475-2480.These fusions are inserted constructs, e.g., pcDNA3.1 (Invitrogen,Carlsbad, Calif.), and expressed in HEK293 cells.

C. FGF23-FcLALA v1

A fusion is constructed which comprises: FGF23, a linker, and FcLALA.This construct is designated FGF23-FcLALA v1 and presented below as SEQID NOs: 50 and 51.

The nucleotide sequence of FGF23-FcLALA v1 (wherein initiation ATG as 1)is presented below as SEQ ID NO: 50.

The amino acid sequence of FGF23(R179Q)-FcLALAv1 is presented below asSEQ ID NO: 51.

In this sequence, the various components of the fusion are as follows:

FGF23: (aa) 1-251; Linker: 252-256; FcLALA: 257-482.

D. FGF23-FcLALA v2

A fusion is constructed which comprises: FGF23-FcLALA v2, whichcomprises FGF23 and FcLALA.

The nucleotide sequence of FGF23-FcLALA v2 (wherein initiation ATG as 1)is presented below as SEQ ID NO: 52.

The amino acid sequence of FGF23(R179Q)-FcLALAv2 is presented below asSEQ ID NO: 53.

In this sequence, the various components of the fusion are as follows:

FGF23: 1-251; Linker: 252-256; FcLALA: 257-473.

Other fusion polypeptides can be constructed by combining in variouscombinations the FGF sequences, modified Fc fragments, and (optionally)linkers, and variants and derivatives thereof, as described herein orknown in the art.

E. Activation of Egr-1-luc reporter gene by sKlotho-FGF23(R179Q)-FcLALAfusion proteins; activation of Egr-1-luc reporter gene byFGF23(R179Q)-FcLALA proteins; and pharmacokinetic profile ofFGF23(R179Q) vs FGF23(R179Q)-FcLaLav2 are determined.

FIG. 7 shows the activation of Egr-1-luc reporter gene bysKlotho-FGF23(R179Q)-FcLALA fusion proteins. HEK293T cells aretransiently transfected with the Egr-1-luc reporter gene and incubatedwith the indicated conditioned media in the absence or presence of 20μg/ml heparin. Luciferase activities are then determined 18 hours later.The result shows that sklotho-FGF23-FcLALA fusion proteins induces thereporter gene activity. These inductions are significantly enhanced inthe presence of heparin. sKF-Fcv1: sKlotho-FGF23-FcLALAv1; sKF-Fcv2:sKlotho-FGF23-FcLALAv2

FIG. 8 shows the activation of Egr-1-luc reporter gene byFGF23(R179Q)-FcLALA proteins. HEK293T cells are transiently transfectedwith the Egr-1-luc reporter gene together with the full-lengthtransmembrane form of Klotho and incubated with the indicated 30%conditioned media. Luciferase activities are then determined 18 hourslater. The results show that FGF23-FcLALA fusion proteins induce thereporter gene activity in a similar manner as the FGF23.

FIG. 9 shows the pharmacokinetic profile of FGF23(R179Q) vsFGF23(R179Q)-FcLALAv2. Four mice per group are injected subcutaneouslywith FGF23(R179Q)-6×His or FGF23(R179Q)-FcLALAv2 at 2 mg/kg. At theindicated times, serum samples are collected and analyzed for FGF23 byELISA. FGF23(R179Q)-FcLALA concentration in serum remains elevated atthe 24 hr time point, while FGF23(R179Q)-6×His is back to basal level.This results indicate that with the addition of FcLALA, the in vivohalf-life of FGF23(R179Q) is significantly improved.

Example 6 In Vivo Efficacy of sKlotho-FGF23 Fusion in Enhancing MuscleGrowth After Dexamethasone-Induced Muscle Atrophy

Experimental data shows that intramuscular injection of sKlotho-FGF23significantly enhanced growth of muscle mass after dexamethasone-inducedmuscle atrophy. In this experiment, the peptide corresponding to that ofSEQ ID NO: 41 is used.

FIG. 10 shows absolute weights (A) and percent weight change (B) of thegastrocnemius-soleus-plantaris (GSP) muscles showing that intramuscularinjection of sKlotho-FGF23 (KLOFGF) significantly enhanced regrowth ofmuscle mass after dexamethasone (DEX)-induced muscle atrophy comparedwith intramuscular injection of sKlotho (sKLO) or phosphate bufferedsaline (PBS).

Eighty male C57BL/6 mice, aged 15 weeks, are randomized by body weightinto 8 groups each of 10 mice. Four groups receive water without DEX(W21d) while the other four receive DEX in drinking water at 2.4mg/kg/day for three weeks (D21d). After the three weeks, DEX treatmentis stopped and one W21d and one D21d group is immediately sacrificed toestablish the degree of muscle atrophy induced by the DEX treatment. Theremaining three groups of W21d or D21d mice are allowed to recover foranother 14 days (R14d) during which period they receive an intramuscularinjection of 2×50 μl of PBS, sKlotho-FGF23 (KLOFGF; 1.6 mg/ml), orsKlotho (sKLO; 1.6 mg/ml), respectively, every other day into the rightgastrocnemius-soleus-plantaris muscle complex. The mice are sacrificed24 h after the last intramuscular injection and the muscle weightsdetermined and expressed as absolute weight (A) or percent changecompared to the W21d+PBS group.

These data show the in vivo efficacy of sKlotho-FGF23 fusion inenhancing muscle growth after dexamethasone-induced muscle atrophy.

Example 7 Additional Mutations in the FGF23 Portion of Fusion ProteinsWhich Reduce Aggregation, Reduce Undesired Protease-Induced Cleavage,and Increase Production

Several mutations are investigated within the FGF23 portion ofsKlotho-FGF23 and FGF23-FcLaLa fusion polypeptides. These include Q156,C206 and C244 (wherein the number is based on the FGF23 amino acidsequence). Example individual mutations include Q156A, C2065 and C244S,and mutations at any of these sites can be combined with a mutation atR179 (e.g., R179Q). Example sequences are provided in SEQ ID NO: 54 to68 of FIGS. 2.

C206 and C244 are suspected to be involved in dimerization; and Q156 isa site identified by the inventors as a protease sensitive site.Mutating these amino acids to any other amino acid enhances thequalities of the proteins, by reducing aggregation, reducing undesiredprotease-induced cleavage, and increasing protein production from cells,without interfering with FGF23 activity. This is an unexpected result,as these three positions are conserved in the FGF23 proteins found inhuman, rhesus, bovine, mouse and rat. This conservation is shown belowin the comparison between SEQ ID NOs: 69, 70, 71, 72 and 73, with theQ156, C206 and C244 in bold, underlined font.

hFGF23 MLGARLRLWVCALCSVCSMSVLRAYPNASPLLGSSWGGLIHLYTATARNSYHLQIHKNGHrhesus MLGARLRLWVCALCSVCSMSVIRAYPNASPLLGSSWGGLIHLYTATARNSYHLQIHKNGHbovine MLGARLGLWVCTLSCV-----VQAYPNSSPLLGSSWGGLTHLYTATARNSYHLQIHGDGHmouse MLGTCLRLLVGVLCTVCSLGTARAYPDTSPLLGSNWGSLTHLYTATARTSYHLQIHRDGH ratMLGACLRLLVGALCTVCSLGTARAYSDTSPLLGSNWGSLTHLYTATARNSYHLQIHRDGH hFGF23VDGAPHQTIYSALMIRSEDAGFVVITGVMSRRYLCMDFRGNIFGSHYFDPENCRFQHQTL rhesusVDGAPHQTIYSALMIRSEDAGFVVITGVMSRRYLCMDFRGNIFGSHYFNPENCRFRHWTL bovineVDGSPQQTVYSALMIRSEDAGFVVITGVMSRRYLCMDFTGNIFGSHHFSPESCRFRQRTL mouseVDGTPHQTIYSALMITSEDAGSVVITGAMTRRFLCMDLHGNIFGSLHFSPENCKFRQWTL ratVDGTPHQTIYSALMITSEDAGSVVIIGAMTRRFLCMDLRGNIFGSYHFSPENCRFRQWTL hFGF23ENGYDVYHSPQYHFLVSLGRAKRAFLPGMNPPPYS Q FLSRRNEIPLIHFNTPI-PRRHTR rhesusENGYDVYHSPQHHFLVSLGRAKRAFLPGMNPPPYS Q FLSRRNEIPLIHFNTPR-PRRHTR bovineENGYDVYHSPQHRFLVSLGRAKRAFLPGTNPPPYA Q FLSRRNEIPLPHFAATARPRRHTR mouseENGYDVYLSQKHHYLVSLGRAKRIFQPGTNPPPFS Q FLARRNEVPLLHFYTVR-PRRHTR ratENGYDVYLSPKHHYLVSLGRSKRIFQPGTNPPPFS Q FLARRNEVPLLHFYTAR-PRRHTR hFGF23SAEDDSERDPLNVLKPRARMTPAPAS C SQELPSAEDNSPMASDPLGVVRGGRVNTHAGGT rhesusSAEDDSERDPLNVLKPRARMTPAPAS C SQELPSAEDNSPVASDPLGVVRGGRVNTHAGGT bovineSAHDSG--DPLSVLKPRARATPVPAA C SQELPSAEDSGPAASDPLGVLRGHRLDVRAGSA mouseSAEDPPERDPLNVLKPRPRATPVPVS C SRELPSAEEGGPAASDPLGVLRRGRGDARGGAG ratSAEDPPERDPLNVLKPRPRATPIPVS C SRELPSAEEGGPAASDPLGVLRRGRGDARRGAG hFGF23GPEG C RPFAKFI (SEQ ID NO: 69) rhesus GPEA C RPFPKFI (SEQ ID NO: 70)bovine GAER C RPFPGFA (SEQ ID NO: 71) mouse GADR C RPFPRFV(SEQ ID NO: 72) rat GTDR C RPFPRFV (SEQ ID NO: 73)

The fact that these three mutations do not prevent FGF23 activity isshown in FIG. 11. This figure shows activation of Egr-1-luc reportergene by FGF23(R179Q)-FcLALA and Q156A, C206S, C244S and C206S/C244Smutants.

HEK293T cells are transiently transfected with the EGR-1-luc reportergene together with the full-length transmembrane form of Klotho andindicated FGF23-FcLaLa mutants. Luciferase activities are thendetermined 18 hours later. The results show that C206S, C244S,C206S/C244S (three independent clones) and Q156A (three independentclones) mutants are equally effective as FGF23-FcLALA fusion proteins inactivating EGR-1-Luc reporter gene activity.

Data showing that mutating C244 and C206 alter dimerization andaggregation of FGF23 is shown in FIG. 12. This figure shows proteinqualities of WT, Q156A, C206S, C244S and C206S/C244S mutants ofFGF23(R179Q)-FcLaLa. Conditioned medium from HEK293T cells transienttransfected with the indicated FGF23-FcLaLa expression vectors areanalyzed by Western blot using an FGF23 antibody. The result shows thatC206S/C244S mutation prevents protein dimerization and Q156A mutationhas reduced proteolytic fragments.

Thus, surprisingly, even though these Q156, C206 and C244 residues areconserved across species, they can mutated without reducing FGF23activity and can enhance the qualities of the protein by reducingaggregation and cleavage and by improving production.

Unless defined otherwise, the technical and scientific terms used hereinhave the same meaning as that usually understood by a specialistfamiliar with the field to which the disclosure belongs.

Unless indicated otherwise, all methods, steps, techniques andmanipulations that are not specifically described in detail can beperformed and have been performed in a manner known per se, as will beclear to the skilled person. Reference is for example again made to thestandard handbooks and the general background art mentioned herein andto the further references cited therein.

Claims to the invention are non-limiting and are provided below.

Although particular embodiments and claims have been disclosed herein indetail, this has been done by way of example for purposes ofillustration only, and is not intended to be limiting with respect tothe scope of the appended claims, or the scope of subject matter ofclaims of any corresponding future application. In particular, it iscontemplated by the inventors that various substitutions, alterations,and modifications may be made to the disclosure without departing fromthe spirit and scope of the disclosure as defined by the claims. Thechoice of nucleic acid starting material or clone of interest isbelieved to be a matter of routine for a person of ordinary skill in theart with knowledge of the embodiments described herein. Other aspects,advantages, and modifications considered to be within the scope of thefollowing claims. Redrafting of claim scope in later filed correspondingapplications may be due to limitations by the patent laws of variouscountries and should not be interpreted as giving up subject matter ofthe claims.

1. A fusion polypeptide comprising: (a) a polypeptide comprisingfibroblast growth factor 23 (FGF23), or a functionally active variant orderivative thereof, wherein FGF23 has a mutation at one or more of thepositions Q156, C206 and C244; and (b) either a modified Fc fragmenthaving decreased affinity for Fc-gamma-receptor and/or increased serumhalf-life, or a polypeptide comprising at least one extracellularsubdomain of a Klotho protein, or a functionally active variant orderivative thereof; and, optionally (c) a linker.
 2. The fusionpolypeptide of claim 1, wherein the polypeptide of (a) is operativelylinked to the N-terminus of the polypeptide of (b).
 3. The fusionpolypeptide of claim 1, wherein the polypeptide of (b) is operativelylinked to the N-terminus of the polypeptide of (a).
 4. The fusionpolypeptide of claim 1, wherein the polypeptide of (a) and thepolypeptide of (b) are connected by a polypeptide linker.
 5. The fusionpolypeptide of claim 4, wherein the polypeptide linker comprises anamino acid sequence selected from the group consisting of SEQ ID NO: 11,SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ ID NO:16, SEQ ID NO: 17, and SEQ ID NO:
 18. 6. The fusion polypeptide of claim4, wherein the polypeptide linker comprises at least 1 and up to about30 repeats of an amino acid sequence selected from the group consistingof SEQ ID NO: 12, SEQ ID NO: 13, SEQ ID NO: 14, SEQ ID NO: 15, SEQ IDNO: 16, SEQ ID NO: 17, and SEQ ID NO:
 18. 7. The fusion polypeptide ofclaim 4, wherein the polypeptide of (a) is connected by a peptide bondto the N-terminus of said polyppetide linker, and the polypeptide of (b)is connected by a peptide bond to the C-terminus of said polypeptidelinker.
 8. The fusion polypeptide of claim 4, wherein the polypeptide of(a) is connected by a peptide bond to the C-terminus of said polypeptidelinker, and the polypeptide of (b) is connected by a peptide bond to theN-terminus of said polypeptide linker.
 9. The fusion polypeptide ofclaim 1, wherein the extracellular subdomain of the Klotho protein is aKL-D1 domain or a KL-D2 domain.
 10. The fusion polypeptide of claim 1,wherein the polypeptide of (a) comprises at least two extracellularsubdomains of the Klotho protein.
 11. The fusion polypeptide of claim10, wherein the at least two extracellular subdomains of the Klothoprotein are at least two KL-D1 domains in tandem repeats.
 12. The fusionpolypeptide of claim 10, wherein the at least two extracellularsubdomains of the Klotho protein are at least two KL-D2 domains intandem repeats.
 13. The fusion polypeptide of claim 10, wherein the atleast two extracellular subdomains of Klotho protein comprise a KL-D1domain and a KL-D2 domain.
 14. The fusion polypeptide of claim 1,wherein the polypeptide of (a) is the extracellular domain of the Klothoprotein.
 15. The fusion polypeptide of claim 1, further comprising asignal peptide.
 16. The fusion polypeptide of claim 15, wherein thesignal peptide is the Klotho signal peptide.
 17. The fusion polypeptideof claim 15, wherein the signal peptide is the IgG signal peptide. 18.The fusion polypeptide of claim 1 that specifically binds to afibroblast growth factor receptor.
 19. The fusion polypeptide of claim1, wherein the Klotho protein is alpha-Klotho.
 20. The fusionpolypeptide of claim 1, wherein the Klotho protein is beta-Klotho. 21.The fusion polypeptide of claim 19, wherein the fibroblast growth factoris fibroblast growth factor-23 (FGF23) or a fibroblast growth factor-23variant (R179Q).
 22. The fusion polypeptide of claim 20, wherein thefibroblast growth factor is fibroblast growth factor-19 or fibroblastgrowth factor-21.
 23. The fusion polypeptide of claim 1 comprising anamino acid sequence which is 95% or more identical to the amino acidsequence of SEQ ID NO: 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65,66, 67, or
 68. 24. The fusion polypeptide of claim 1 having the aminoacid sequence of SEQ ID NO: 58, or SEQ ID NO:
 68. 25. The fusionpolypeptide of claim 1 comprising FcLALA.
 26. A pharmaceuticalcomposition comprising the fusion polypeptide of claim 1 and apharmaceutically acceptable carrier.
 27. A nucleic acid comprising asequence that encodes the fusion polypeptide of claim
 1. 28. A host cellcontaining the nucleic acid of claim
 27. 29. A vector comprising thenucleic acid of claim
 27. 30. A method for treating or preventing anage-related condition in an individual, comprising administering to anindividual in need thereof a therapeutically effective dose of apharmaceutical composition comprising a fusion polypeptide comprising:(a) a polypeptide comprising fibroblast growth factor 23 (FGF23), or afunctionally active variant or derivative thereof, wherein FGF23 has amutation at one or more of the positions Q156, C206 and C244; and (b)either a modified Fc fragment having decreased affinity forFc-gamma-receptor and/or increased serum half-life, or a polypeptidecomprising at least one extracellular subdomain of a Klotho protein, ora functionally active variant or derivative thereof; and, optionally (c)a linker.
 31. The method of claim 30, wherein the age-related conditionis selected from the group consisting of sarcopenia, skin atrophy,muscle wasting, brain atrophy, atherosclerosis, arteriosclerosis,pulmonary emphysema, osteoporosis, osteoarthritis, immunologicincompetence, high blood pressure, dementia, Huntington's disease,Alzheimer's disease, cataracts, age-related macular degeneration,prostate cancer, stroke, diminished life expectancy, memory loss,wrinkles, impaired kidney function, and age-related hearing loss. 32.The method of claim 30, wherein the Klotho protein is alpha Klothoprotein.
 33. The method of claim 31, wherein the age-related conditionis muscle wasting, the Klotho protein is alpha Klotho protein, and thefibroblast growth factor is fibroblast growth factor
 23. 34. A methodfor treating or preventing a metabolic disorder in an individual,comprising administering to an individual in need thereof atherapeutically effective dose of a pharmaceutical compositioncomprising a fusion polypeptide, comprising: (a) a polypeptidecomprising fibroblast growth factor 23 (FGF23), or a functionally activevariant or derivative thereof, wherein FGF23 has a mutation at one ormore of the positions Q156, C206 and C244; and (b) either a modified Fcfragment having decreased affinity for Fc-gamma-receptor and/orincreased serum half-life, or a polypeptide comprising at least oneextracellular subdomain of a Klotho protein, or a functionally activevariant or derivative thereof; and, optionally (c) a linker.
 35. Themethod of claim 34, wherein the metabolic disorder is selected from thegroup consisting of Type II Diabetes, Metabolic Syndrome, hyperglycemia,and obesity.
 36. The method of claim 34, wherein the fusion polypeptidecomprises: (a) a polypeptide that comprises at least one extracellularsubdomain of a beta-Klotho protein; and (b) a polypeptide that comprisesa fibroblast growth factor
 21. 37. A method for treating or preventinghyperphosphatemia or calcinosis in an individual, comprisingadministering to an individual in need thereof a therapeuticallyeffective dose of a pharmaceutical composition comprising a fusionpolypeptide, comprising: (a) a polypeptide comprising fibroblast growthfactor 23 (FGF23), or a functionally active variant or derivativethereof, wherein FGF23 has a mutation at one or more of the positionsQ156, C206 and C244; and (b) either a modified Fc fragment havingdecreased affinity for Fc-gamma-receptor and/or increased serumhalf-life, or a polypeptide comprising at least one extracellularsubdomain of a Klotho protein, or a functionally active variant orderivative thereof; and, optionally (c) a linker.
 38. The method ofclaim 37, wherein the fusion polypeptide comprises: (a) a polypeptidethat comprises at least one extracellular subdomain of an alpha Klothoprotein; and (b) a polypeptide that comprises a fibroblast growth factor23.
 39. A method for treating or preventing chronic renal disease orchronic renal failure in an individual, comprising administering to anindividual in need thereof a therapeutically effective dose of apharmaceutical composition comprising a fusion polypeptide, comprising:(a) a polypeptide comprising fibroblast growth factor 23 (FGF23), or afunctionally active variant or derivative thereof, wherein FGF23 has amutation at one or more of the positions Q156, C206 and C244; and (b)either a modified Fc fragment having decreased affinity forFc-gamma-receptor and/or increased serum half-life, or a polypeptidecomprising at least one extracellular subdomain of a Klotho protein, ora functionally active variant or derivative thereof; and, optionally (c)a linker.
 40. The method of claim 39, wherein the Klotho protein isalpha Klotho protein.
 41. A method for treating or preventing cancer inan individual, comprising administering to an individual in need thereofa therapeutically effective dose of a pharmaceutical compositioncomprising a fusion polypeptide, comprising: (a) a polypeptidecomprising fibroblast growth factor 23 (FGF23), or a functionally activevariant or derivative thereof, wherein FGF23 has a mutation at one ormore of the positions Q156, C206 and C244; and (b) either a modified Fcfragment having decreased affinity for Fc-gamma-receptor and/orincreased serum half-life, or a polypeptide comprising at least oneextracellular subdomain of a Klotho protein, or a functionally activevariant or derivative thereof; and, optionally (c) a linker.
 42. Themethod of claim 41, wherein the cancer is breast cancer.
 43. The methodof claim 41, wherein the Klotho protein is an alpha Klotho protein. 44.The fusion polypeptide of claim 1, wherein the Klotho protein is a humanKlotho protein.
 45. The fusion polypeptide of claim 1 for use intreating or preventing muscle atrophy.
 46. A method of treating orpreventing muscle atrophy comprising (consisting essentially of, orconsisting of) administering to an individual in need thereof atherapeutically effective dose of a pharmaceutical compositioncomprising a soluble Klotho fusion protein of SEQ ID NO: 47, or SEQ IDNO:
 49. 47. A method of treating or preventing muscle atrophy comprising(consisting essentially of, or consisting of) administering to anindividual in need thereof a therapeutically effective dose of apharmaceutical composition comprising (a) a polypeptide comprisingfibroblast growth factor 23 (FGF23), or a functionally active variant orderivative thereof, wherein FGF23 has a mutation at one or more of thepositions Q156, C206 and C244; and (b) either a modified Fc fragmenthaving decreased affinity for Fc-gamma-receptor and/or increased serumhalf-life, or a polypeptide comprising at least one extracellularsubdomain of a Klotho protein, or a functionally active variant orderivative thereof; and, optionally (c) a linker.